"Exactly 0 or 0 Armatures must be selected": This is misleading, you are trying to import an SSE animation file instead of an LE one OR you are importing using the incorrect skeleton originally used to make the animation. Kudos to dinodietonight for debugging and testing it out!
I just tried out this rig today but I've got a lot of questions for how to operate the first-person rig if you or anyone else feels up to answering. I've been using Blender 4.4.3. I switched between that and 4.0. a few times; no differences.
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First, I noticed controller visibility options on the first-person rig aren't working as intended. Third-person seems fine. Finger controllers are always visible and even toggling the layer directly doesn't affect them. NickNak's toggles operated fine on my end. Weapons Ctrl, Magic Ctrl, AnimObject Ctrl, twist bones, etc. are having this issue.
Second, and this is more general animation but my brain really turns off when it comes to rigging and constraints and the rest. Working with weapons in first-person—what is the hierarchy of the weapon controllers (regular, Export and IK). I noticed the IK and Export controllers are parented to the left hand while the other is parented to the right which created a strange doubling of transforms. This issue didn't happen with a newly-added weapon model following your article's import tutorial as whatever constraints that be are not specified within that tutorial so it sits happily on one hand. I'm not really sure how to interpet all of it, that's all.
Third, also more general rigging/animation, I'm wondering how you would go about animating something like a warhammer where two hands are spaced out along the weapon. How, using this rig, would someone set up the hands being bound to the weapon where articulation of the hands is still separate from the weapon? How do you constrain the non-dominant hand to the weapon so you don't have to eyeball it every time the dominant hand moves the weapon? How would exporting interpret new controllers or constraints? Do the exporting actions that convert all keys to frames bake all that information?
On the note of weapon constraints, the weapon controller as it is currently set up is a direct child of the right hand controller which is the same controller used to rotate the hand itself. At that configuration, if you decide the angle at which the wrist is sitting doesn't suit you later into animating, you can't really undo it because it will move the weapon out of place. I guess I'm looking for a sort of separation of the hierarchy there if its possible. A bit like:
right hand->right hand wrist->right hand fingers right hand->weapon right
If you're familiar with tktk's rigs, this was done by moving the hands with IK forearm controllers which left the wrists free to move around. Correct me if I'm wrong on its use case, I really do not animate or rig enough to know just how technical I'm getting.
Fourth. Not really a big deal cuz I can sort it out manually but I think it's worth mentioning—the last two digits of each finger shouldn't be able to rotate on any axis other than local X. Speeds up animating to not have to hit the X key each time you go to rotate.
I hope the questions aren't too ignorant, I'm just very out of my wheelhouse when it comes to animating in Skyrim and the interfacing of a rig to how it ultimately is interpreted by the game. I want to animate a two-handed weapon and I'm trying to overcome the logistics of the whole thing before I start commiting the time to animating and finding out halfway through that I've been using the rig incorrectly.
1. The controller visibility options do work as intended, I just tested it again, it's the same script in-between the 3rd and 1st person rigs, and it's possibly not toggling bones because you already have a bone collection visible, like Import Bones, that would include all of the FK bones, including the finger bones, etc.
2. The weapon IK parent you can switch between either the right hand, the left hand, or neither. This means that if you wanted the weapon bone to track the left hand instead of default the right hand, like in vanilla Skyrim, you can do that for any animations where you are holding something in your left hand. If you turned both the left and right hand tracking off, then it is unparented to both and technically parented to the world space, which is unaffected by the rig movement.
3. Since a warhammer is long and the hand movement will not change much with it, you can create an initial position of holding the warhammer using the IK hand bones, and set a bone constraint for the IK left bone to be 'Child Of' the IK right hand bone. That would enable the left hand to track, using its initial position for the rest of the animation.
4. The hand rotation is practically the wrist. The skeleton matches 1:1 with what is in-game. If you're suggesting to add a wrist bone, I don't think it would make a difference. Also, the IK hand bones have parent switches if you want the hands to move independent of the rig with 4 different options.
5. You could always lock the axes yourself if you wanted to, but maybe someone wants to animate broken fingers :)
EDIT: I added two articles and a screenshot for setting up the HKANNO64 folder.
Thanks for the reply and for going as far as to setup two new articles, that's a lot of work! I'll spend some more time messing with the controls and see if I can't get the hang of things. On the visibility topic, thanks for pointing out the Import Bones toggle and clarifying what its there for.
You wouldn't happen to have instruction on how to make your rig? Particularly with rigging the skeleton data? I'm looking to import some animations from Skyrim onto Fallout 4, and some Fallout 4 animations onto Skyrim.
I'm not sure what you're asking, because I didn't make the original rigs. I improved them with updated/fixed scripts, fixed bones, bugs, etc. but Nickanak originally made the rigs from scratch.
if I export first person animations with forward axis -Z and up axis Y, the arms go upward off-screen
but if I export them with forward axis Y and up axis Z, the hands become distorted. what gives?
I did choose 1skeleton.hkx as the primary skeleton.
these issues are only with the first person rig
edit: in version 2.3, if I import a first person animation, the body moves up a little bit, and if I click "fix import", the body moves up even further. plus the arm models remain T-posed and not attached to the arm bones, when I import an animation. they become attached, if I click "action" next to "FK", under "IK FK Controls [ALL LIMBS]", AFTER importing the animation, but the weapon model gets tossed to the character's left side, away from the hand.
edit2: in version 2.2, only the issue with the body being moved up a bit is present. the arm and weapon models are attached properly.
Yep, the issue with earlier versions or in between was that the looknode bone was rotated 90 degrees between the import and export rig, so on export the looknode bone rotated basically the ingame skeleton backwards by 90 degrees. You can fix it if you have existing animation files by making the rotation of the looknode bone in the controll rig root armature match the rotation in the deform rig in EDIT mode.
The reason the rig moves upwards is because on import, the pelvis bone or whichever bones it is that are parent to all the other bones in the rig are shifted upward. You can basically zero the position of the pelvis or root bones or npc com bones and it'll fix that weird offset you're seeing. The import/export plugin is somewhat buggy but the 'FIX IMPORT' button should usually take care of all those issues.
As for why the weapon goes off to the side, you possibly have it set to track the left hand instead of the right hand and it's set to IK mode. You want to make sure the UI has it tracking the right hand as you'd expect.
ok rn only the issue with the rig moving upwards remains. working with 2.3 now. (I did your weapon fix successfully. for some reason, it was tracking both hands. I didn't mess with it, it was like that by default, so I made it only track the right hand)
I can't do your fix, because the parent bone (NPC Root [Root]) is already at y=0. the problem is that, once the hkx is imported, the body not only moves up a little, but also gets stretched. "fix import" fixes the stretching, but it does so by moving it further upwards.
I don't know if it's a good idea to ignore the fact that the parent bone is at y=0 and just move it downwards regardless.
edit: Issue Solved...I think! ok this is strange... the stretching doesn't happen when I leave the "primary skeleton" at its default path "D:\src\aaBlenderWorkingDir\Nickanak's Attempt\HKX exporter\1skeleton.hkx"
if I type the path of the 1skeleton.hkx at HKX exporter, the stretching happens. hooray, I guess, but what gives?
I still have to press the action button to attach the arm model to the arm bones...am I supposed to do this?
Like I mentioned, the plugin is buggy and working as intended with the correct skeleton selected. You can use the 'Fix Import' button to fix the stretching or manually fix it by zeroing which ever parent/root bones in pose mode.
Yes, you're supposed to use the snap buttons if you're using the IK bones, and snapping from IK to FK will make the IK bones snap to the FK bones. Instructions are included in the readme and articles.
sorry, for bothering you, but another problem came up. it turns out that the arm model is not affected by the arm bones at all. pressing the action key seems to only arrange/overlay them together after import, but after that, moving/rotating the arm bones doesn't move the arm models.
the strange thing is, every other part of the body, even the fingers, is properly attached to its corresponding bone, all except the arms...
namely these bones (both left and right): upper_arm FK, forearm FK, and hand FK
could you double-check, in case you also encounter this problem? cuz I didn't do anything with the rig that could possibly cause it
edit: ok, since 2.2 doesn't have this issue, imma stick with it
Hey there, I'm experimenting with some rigs and found yours.. I'm trying to use it to import and work with vanilla animations, but I can't seem to find how to toggle the "rig tools" UI and the the "Gizmos" to move the bones and such..
Did you manage to make an exported first person animation work properly in-game? If so, could you please tell me your workflow? Been having issues with the first person rig
Yeah, I managed to make some first person animations.
First I installed the HKX plugin, then I moved the necessary bones at certain frames that I needed with the control rig, and when I was done, I clicked on the switch rigs button to go to the deform rig, selected all bones there and used the export function with HKX, also set the primary skeleton too. And it worked in game.
did the body not get stretched or moved upwards when you imported the hkx to the rig? cuz I'm having this issue. what blender version are you on? mine is 4.4.3
edit: Issue Solved...I think! ok this is strange... the stretching doesn't happen when I leave the "primary skeleton" at its default path "D:\src\aaBlenderWorkingDir\Nickanak's Attempt\HKX exporter\1skeleton.hkx"
if I type the path of the 1skeleton.hkx at HKX exporter, the stretching happens
Hey, im probably an idiot, but how do i move limb bones around so that other bones will follow? Like, i take a right hand bone and move it, and it just detaches from arm bone, instead of arm bone following the hand one. I tried playing around with FK/IK buttons in rig options, but haven't been able to make it so that bones work together, idk how to explain it better.
Those are the wrong bones to look at. You're looking at the FK bones which do not track the IK bones unless you snap the FK bones to IK using the buttons to snap for a specific frame or by using the Action buttons.
Ohh, now I get it. I thought they should move automatically, sorry lol.. I can animate the IK bones and then later use the snap action so the FK bones are snapped for all frames (or vice versa)..
Still getting used to this rig, the import stuff is a major thing for me, thanks a lot.
I have. I actually recommend using PyNifly for importing any weapon meshes into the scene in one of my articles. However, that's a completely different plugin and workflow for animation handling, which these rigs are not built for. To make a workflow for PyNifly from scratch is a big time commitment, and I don't have time between work and Somnium development.
EDIT: I was curious, and looking at PyNifly's documentation it explicitly says that it only supports Skyrim LE:
I am not sure besides importing an existing animation that an actor uses for a furniture mesh, importing a specific mesh you can reference in-game, and aligning the position of the furniture mesh with the rig so that it matches what looks like in-game. You could make the mesh of the chair match any bone of the rig if you're familiar with Blender, but that's how I would do it.
I'm posting this both here and on NickaNak's rig since the problems affect both.
I kept getting the "Exactly 0 or 0 Armatures must be selected" error whenever I tried to import some animations. After a couple days, I managed to isolate the problem to 2 causes:
1. The file is formatted incorrectly. For some reason, some animations would be labeled an hkx file but would be structured like an xml file. As in it would be called "anim.hkx" but opening it in notepad++ shows it structured like an xml file instead of the wall of random characters and NUL that you expect. Sometimes changing the .hkx to .xml allows it to be converted by a converter, but not always. No idea what can be done about that.
2. The skeleton doesn't have enough bones. The included skeleton.hkx and xpskeleton.hkx have 99 and 156 bones respectively. This works for vanilla animations and some modded ones, but some animations (including most of the ones I wanted to import) need a skeleton with 242 bones. This matches the XPMS rig rather than than the 156-bone XPMSE rig. This can be fixed easily by just adding the missing skeleton. It would also be nice to add something to detect which skeleton to use automatically during the importing process rather than need to manually specify the skeleton.
Another problem I found after importing is that many animations that use either the 156-bone or 242-bone skeleton will have some sort of transformation effect (location, rotation, and/or scale) on bones that shouldn't be affected. They will even affect locked transforms.
Anyway this rig is fantastic. I'm not using it to make animations for skyrim but instead using it to render skyrim animations in blender. It works great for that (apart from the issue mentioned above).
"Exactly 0 or 0 Armatures must be selected" > this is a misleading error. It complains about that if you have two armatures visible and highlighted. All you need to do is go to the outliner menu, make sure only one armature is visible, click on the correct armature to import onto (Controll Rig Root), go to POSE mode, press A to select all, and import following the instructions.
Importing with the plugin does not require all bones to exist from a given skeleton. It imports onto the rig based on the hkx bone names defined for each bone of the rig, assuming the bone is already mismatched in name from the skeleton. If the names match, then the importer plugin imports fine, otherwise if there is no match and no defined hkx target bone, it just doesn't import for those unmatched bones.
You are correct in that importing animations has some transform effect on certain bones, probably because the rigs used to make those animations don't lock those bones. If you like, you can unlock whatever transforms for whichever bones and pray it works.
EDIT: I misread/half understood what you meant with the bones missing, because you want to use a special skeleton that has MORE bones than the XPMSE rig. It's actually very difficult already to update the rig, because the orientations and everything of all the bones are not the same orientation as the bones from just importing an animation straight from the plugin with no existing armature or rig. I would basically have to recreate this entire rig from scratch, which I could theoretically do... but Nickanak did the heavy lifting in that regard and I would have to learn how to basically create a rig fully from end to end with IK/FK, bone weighting for the correct meshes (assuming I import the correct meshes for the limbs), rewriting all the scripts for IK/FK... I just don't think I have time to make a custom rig like that (at least for a while).
At least for my purposes, I don't think that remaking the rig is really necessary. Most of the bones in the XP skeleton are found in the 242-bone skeleton, it's just missing a bunch of bones for stuff like hair and cloak physics that aren't ever used for actual animation (which is why they were removed in xpmse). If the rig is meant for the XPMSE skeleton, it shouldn't need adaptation.
The issue of borked transforms seems to be a mapping issue at the import-level rather than a rigging-issue. It usually manifests as the model being rotated at a weird angle and with the model stretching and squishing over the course of the animation. It also happens with some animations meant for the XPMSE skeleton, so it's probably related to bones that they have that the vanilla skeleton doesn't. I'm not at my computer right now so I can't confirm until later, but I think it has something to do with the NPC ROOT, NPC COM, and the NPC Pelvis bones having their properties incorrectly applied.
For a short-term fix, just adding the extra skeleton file (I got mine from the xpms modders ressources download https://www.nexusmods.com/skyrim/mods/26800?tab=files) to the same folder as the already included skeleton.hkx and xpskeleton.hkx would help a lot.
I am able to recreate that error about Exactly 0 or 0 Armatures must be selected... I'll fix it and and include the skeleton as well.
EDIT: I can verify now that I was getting that error when attempting to import an SSE animation file, not a backported LE animation file. I will add an FAQ here.
It's not due to being an SSE animation instead of an LE animation because I just tested 3 LE mods: Feminine Running and New Dash Animation Feminine Pickup Animation Pretty Combat Animations (PCA) With the running animation I only tested mt_runforward and with PCA I only tested sneakmtidle in the "01 sneak 01" folder. Out of all 3 only PCA successfully imported using the regular skeletons. I then used Hkx Conversion Tool to convert the hkx files to xml and looked at the "annotationTracks" element of the animation object (aka the number of bones that the animation references). The PCA animation has 99 tracks, the running animation has 229 tracks, and the pickup animation has 242 tracks. I also tried using convert-xml-hkx-kf in case it was converting wrong and the files were identical. When I tried importing the 2 unsuccessful animations with the 242-bone skeleton, it worked.
I've also tried using the 242-bone skeleton to import an SSE animation and it doesn't work.
If you want to test it yourself, I've uploaded the skeleton here. I just change the secondary skeleton when importing to this one.
I see, thanks for pointing that out! I'll push out an update most likely tomorrow that fixes some things like some of the export bones not properly matching the deform bones for both third and first person, includes that 242 skeleton, and the XP skeleton (assuming that's different).
Thank you. This rig has been otherwise fantastic to work with and I appreciate the work you put into it.
If it's any help, I think I've narrowed down the weird scaling/rotation/flipping issue with 242-bone animations to being related to the NPC COM bone. In all the busted animations, the character's hips are moving/rotating a lot and the amount the model is stretched on any frame is related to how much the hips are moved/rotated in the animation. At the same time, I've found a few animations that keep the hips steady or only move them up and down and they have no distortion.
when I import animations, the skeleton becomes twisted. I'm using this tool to convert SE anims to LE.
I'm facing the same issue with NickaNak's rig
edit: ok somehow some way...the rig, the plugin, everything works perfectly... maybe because I updated to blender 4.4? I don't remember. it's worth noting, though, that NickaNak's rig still doesn't work for me. the skeleton gets twisted, but this rig works fine.
63 comments
I can help you.
"Exactly 0 or 0 Armatures must be selected": This is misleading, you are trying to import an SSE animation file instead of an LE one OR you are importing using the incorrect skeleton originally used to make the animation. Kudos to dinodietonight for debugging and testing it out!
Second, and this is more general animation but my brain really turns off when it comes to rigging and constraints and the rest. Working with weapons in first-person—what is the hierarchy of the weapon controllers (regular, Export and IK). I noticed the IK and Export controllers are parented to the left hand while the other is parented to the right which created a strange doubling of transforms. This issue didn't happen with a newly-added weapon model following your article's import tutorial as whatever constraints that be are not specified within that tutorial so it sits happily on one hand. I'm not really sure how to interpet all of it, that's all.
Third, also more general rigging/animation, I'm wondering how you would go about animating something like a warhammer where two hands are spaced out along the weapon. How, using this rig, would someone set up the hands being bound to the weapon where articulation of the hands is still separate from the weapon? How do you constrain the non-dominant hand to the weapon so you don't have to eyeball it every time the dominant hand moves the weapon? How would exporting interpret new controllers or constraints? Do the exporting actions that convert all keys to frames bake all that information?
On the note of weapon constraints, the weapon controller as it is currently set up is a direct child of the right hand controller which is the same controller used to rotate the hand itself. At that configuration, if you decide the angle at which the wrist is sitting doesn't suit you later into animating, you can't really undo it because it will move the weapon out of place. I guess I'm looking for a sort of separation of the hierarchy there if its possible. A bit like:
right hand->right hand wrist->right hand fingers
right hand->weapon right
If you're familiar with tktk's rigs, this was done by moving the hands with IK forearm controllers which left the wrists free to move around. Correct me if I'm wrong on its use case, I really do not animate or rig enough to know just how technical I'm getting.
Fourth. Not really a big deal cuz I can sort it out manually but I think it's worth mentioning—the last two digits of each finger shouldn't be able to rotate on any axis other than local X. Speeds up animating to not have to hit the X key each time you go to rotate.
I hope the questions aren't too ignorant, I'm just very out of my wheelhouse when it comes to animating in Skyrim and the interfacing of a rig to how it ultimately is interpreted by the game. I want to animate a two-handed weapon and I'm trying to overcome the logistics of the whole thing before I start commiting the time to animating and finding out halfway through that I've been using the rig incorrectly.
2. The weapon IK parent you can switch between either the right hand, the left hand, or neither. This means that if you wanted the weapon bone to track the left hand instead of default the right hand, like in vanilla Skyrim, you can do that for any animations where you are holding something in your left hand. If you turned both the left and right hand tracking off, then it is unparented to both and technically parented to the world space, which is unaffected by the rig movement.
3. Since a warhammer is long and the hand movement will not change much with it, you can create an initial position of holding the warhammer using the IK hand bones, and set a bone constraint for the IK left bone to be 'Child Of' the IK right hand bone. That would enable the left hand to track, using its initial position for the rest of the animation.
4. The hand rotation is practically the wrist. The skeleton matches 1:1 with what is in-game. If you're suggesting to add a wrist bone, I don't think it would make a difference. Also, the IK hand bones have parent switches if you want the hands to move independent of the rig with 4 different options.
5. You could always lock the axes yourself if you wanted to, but maybe someone wants to animate broken fingers :)
EDIT: I added two articles and a screenshot for setting up the HKANNO64 folder.
but if I export them with forward axis Y and up axis Z, the hands become distorted. what gives?
I did choose 1skeleton.hkx as the primary skeleton.
these issues are only with the first person rig
edit: in version 2.3, if I import a first person animation, the body moves up a little bit, and if I click "fix import", the body moves up even further. plus the arm models remain T-posed and not attached to the arm bones, when I import an animation. they become attached, if I click "action" next to "FK", under "IK FK Controls [ALL LIMBS]", AFTER importing the animation, but the weapon model gets tossed to the character's left side, away from the hand.
edit2: in version 2.2, only the issue with the body being moved up a bit is present. the arm and weapon models are attached properly.
The reason the rig moves upwards is because on import, the pelvis bone or whichever bones it is that are parent to all the other bones in the rig are shifted upward. You can basically zero the position of the pelvis or root bones or npc com bones and it'll fix that weird offset you're seeing. The import/export plugin is somewhat buggy but the 'FIX IMPORT' button should usually take care of all those issues.
As for why the weapon goes off to the side, you possibly have it set to track the left hand instead of the right hand and it's set to IK mode. You want to make sure the UI has it tracking the right hand as you'd expect.
I can't do your fix, because the parent bone (NPC Root [Root]) is already at y=0. the problem is that, once the hkx is imported, the body not only moves up a little, but also gets stretched. "fix import" fixes the stretching, but it does so by moving it further upwards.
I don't know if it's a good idea to ignore the fact that the parent bone is at y=0 and just move it downwards regardless.
edit: Issue Solved...I think! ok this is strange... the stretching doesn't happen when I leave the "primary skeleton" at its default path "D:\src\aaBlenderWorkingDir\Nickanak's Attempt\HKX exporter\1skeleton.hkx"
if I type the path of the 1skeleton.hkx at HKX exporter, the stretching happens. hooray, I guess, but what gives?
I still have to press the action button to attach the arm model to the arm bones...am I supposed to do this?
Yes, you're supposed to use the snap buttons if you're using the IK bones, and snapping from IK to FK will make the IK bones snap to the FK bones. Instructions are included in the readme and articles.
the strange thing is, every other part of the body, even the fingers, is properly attached to its corresponding bone, all except the arms...
namely these bones (both left and right): upper_arm FK, forearm FK, and hand FK
could you double-check, in case you also encounter this problem? cuz I didn't do anything with the rig that could possibly cause it
edit: ok, since 2.2 doesn't have this issue, imma stick with it
This is how the 1st person rig opens:
but that didn't work
Edit: Turns out blender 4.0 wasn't correctly installed lol.First I installed the HKX plugin, then I moved the necessary bones at certain frames that I needed with the control rig, and when I was done, I clicked on the switch rigs button to go to the deform rig, selected all bones there and used the export function with HKX, also set the primary skeleton too. And it worked in game.
edit: Issue Solved...I think! ok this is strange... the stretching doesn't happen when I leave the "primary skeleton" at its default path "D:\src\aaBlenderWorkingDir\Nickanak's Attempt\HKX exporter\1skeleton.hkx"
if I type the path of the 1skeleton.hkx at HKX exporter, the stretching happens
I can animate the IK bones and then later use the snap action so the FK bones are snapped for all frames (or vice versa)..
Still getting used to this rig, the import stuff is a major thing for me, thanks a lot.
Exception: HKANNO64.exe not found -> Aborting
It also says what you need to do in the README.
I believe it has support for SSE HKX files
EDIT: I was curious, and looking at PyNifly's documentation it explicitly says that it only supports Skyrim LE:
also, what would be the proper way to append this project into a preexisting project, and parenting a different body to it?
I kept getting the "Exactly 0 or 0 Armatures must be selected" error whenever I tried to import some animations. After a couple days, I managed to isolate the problem to 2 causes:
1. The file is formatted incorrectly. For some reason, some animations would be labeled an hkx file but would be structured like an xml file. As in it would be called "anim.hkx" but opening it in notepad++ shows it structured like an xml file instead of the wall of random characters and NUL that you expect. Sometimes changing the .hkx to .xml allows it to be converted by a converter, but not always. No idea what can be done about that.
2. The skeleton doesn't have enough bones. The included skeleton.hkx and xpskeleton.hkx have 99 and 156 bones respectively. This works for vanilla animations and some modded ones, but some animations (including most of the ones I wanted to import) need a skeleton with 242 bones. This matches the XPMS rig rather than than the 156-bone XPMSE rig. This can be fixed easily by just adding the missing skeleton. It would also be nice to add something to detect which skeleton to use automatically during the importing process rather than need to manually specify the skeleton.
Another problem I found after importing is that many animations that use either the 156-bone or 242-bone skeleton will have some sort of transformation effect (location, rotation, and/or scale) on bones that shouldn't be affected. They will even affect locked transforms.
Anyway this rig is fantastic. I'm not using it to make animations for skyrim but instead using it to render skyrim animations in blender. It works great for that (apart from the issue mentioned above).
Importing with the plugin does not require all bones to exist from a given skeleton. It imports onto the rig based on the hkx bone names defined for each bone of the rig, assuming the bone is already mismatched in name from the skeleton. If the names match, then the importer plugin imports fine, otherwise if there is no match and no defined hkx target bone, it just doesn't import for those unmatched bones.
You are correct in that importing animations has some transform effect on certain bones, probably because the rigs used to make those animations don't lock those bones. If you like, you can unlock whatever transforms for whichever bones and pray it works.
EDIT: I misread/half understood what you meant with the bones missing, because you want to use a special skeleton that has MORE bones than the XPMSE rig. It's actually very difficult already to update the rig, because the orientations and everything of all the bones are not the same orientation as the bones from just importing an animation straight from the plugin with no existing armature or rig. I would basically have to recreate this entire rig from scratch, which I could theoretically do... but Nickanak did the heavy lifting in that regard and I would have to learn how to basically create a rig fully from end to end with IK/FK, bone weighting for the correct meshes (assuming I import the correct meshes for the limbs), rewriting all the scripts for IK/FK... I just don't think I have time to make a custom rig like that (at least for a while).
The issue of borked transforms seems to be a mapping issue at the import-level rather than a rigging-issue. It usually manifests as the model being rotated at a weird angle and with the model stretching and squishing over the course of the animation. It also happens with some animations meant for the XPMSE skeleton, so it's probably related to bones that they have that the vanilla skeleton doesn't. I'm not at my computer right now so I can't confirm until later, but I think it has something to do with the NPC ROOT, NPC COM, and the NPC Pelvis bones having their properties incorrectly applied.
For a short-term fix, just adding the extra skeleton file (I got mine from the xpms modders ressources download https://www.nexusmods.com/skyrim/mods/26800?tab=files) to the same folder as the already included skeleton.hkx and xpskeleton.hkx would help a lot.
EDIT: I can verify now that I was getting that error when attempting to import an SSE animation file, not a backported LE animation file. I will add an FAQ here.
Feminine Running and New Dash Animation
Feminine Pickup Animation
Pretty Combat Animations (PCA)
With the running animation I only tested mt_runforward and with PCA I only tested sneakmtidle in the "01 sneak 01" folder. Out of all 3 only PCA successfully imported using the regular skeletons. I then used Hkx Conversion Tool to convert the hkx files to xml and looked at the "annotationTracks" element of the animation object (aka the number of bones that the animation references). The PCA animation has 99 tracks, the running animation has 229 tracks, and the pickup animation has 242 tracks. I also tried using convert-xml-hkx-kf in case it was converting wrong and the files were identical. When I tried importing the 2 unsuccessful animations with the 242-bone skeleton, it worked.
I've also tried using the 242-bone skeleton to import an SSE animation and it doesn't work.
If you want to test it yourself, I've uploaded the skeleton here. I just change the secondary skeleton when importing to this one.
If it's any help, I think I've narrowed down the weird scaling/rotation/flipping issue with 242-bone animations to being related to the NPC COM bone. In all the busted animations, the character's hips are moving/rotating a lot and the amount the model is stretched on any frame is related to how much the hips are moved/rotated in the animation. At the same time, I've found a few animations that keep the hips steady or only move them up and down and they have no distortion.
I'm facing the same issue with NickaNak's rig
edit: ok somehow some way...the rig, the plugin, everything works perfectly... maybe because I updated to blender 4.4? I don't remember. it's worth noting, though, that NickaNak's rig still doesn't work for me. the skeleton gets twisted, but this rig works fine.
and for that, I say, thank you!