When your crosshair turn red when you're trying to summon a creature to far away,
the crosshair in the mounted horse combat disappear. This is a vanilla bug.
Tools used to create this:
JPEXS Decompiler
Sothink SWF Decompiler
This mod was tested using a 800x600 resolution. I don't know how it's gonna be in a higher resolution than this. Please let me know!
Extra info:
The reason crosshairs mods here in nexus for Legendary Edition always bug the mounted combat crosshair;
It's because people use the hudmenu.gfx from the Interface.bsa, and actually there's another hudmenu.gfx from the Update.bsa. That's the file you need to use, and not from the Interface.bsa. This way it won't bug the mounted combat crosshair.