1.
In Default PrettyMotion.ini "CustomPose= is already set to 1.

2.
Once you load your game save, It will renew your PrettyMotion MCM List Data, You should save it again, So PrettyMotion will save the renew list aswell. PrettyMotion.ini "CustomPose=" will go back to "0" automatic.

3.
Make sure you have change SKSE\Plugins\PrettyMotion.ini "CustomPose=1" with "notepad++". (you can't just use wordpad or notebook to change it) If you want to renew your PrettyMotion List for other gamesave. Eg: that save was used to play PrettyMotion older version / Poses List has modiffer by youself.

Everytime you want to renew poses list for your different gamesave, make sure you have set "CustomPose=1" in SKSE\Plugins\PrettyMotion.ini.

Just Remember! Once you load your game save, Once PrettyMotion MCM List has update, Please Save it again, Otherwise next time you load this save it will still show old poses list data without update.

4.
If your animobject show weird color, You can manully disable "BSLightingShaderProperty" Shader Flags Environment Mapping properties in the animobject nif, This problems should just happen with darksoul or warriorwithin weapon nif.

5.
I am using "MaximumSkeletonExtended" with "EnhanceCharacterEdit" and "EnhancedCharacterEditEnhancer" and scale character hands to Maximum size in racemenu for testing my poses that animobject can prefectly fit holding in hands, So you probably required same as my character setup enviroment or mods for fit to holding weapon animobjects.

6.
Most pose is design for female character, only few poses is for male or good to use for male character(Eg: Witcher/ Samurai), So some poses when play on male the animojbect may not fit to hold in male character hands.