I don't know how that's possible as the bones are both the same in Blender when I imported both the Animation FBX and the Character's FBX, and I also Exported them from the same file and have not touched the bone names. Can you show me an error or something?
Ok, From what I see, the problem might be "root_x" not being named "Hip" or "Pelvis" as "Root" is the Root bone for both the character and the Animations rigs, so try renaming "root_x" to "Hip" , "Pelvis" or something else and see if that helps.
I have tried this and there are still a bunch of bones like twist bones etc that are not in the animation skeleton but in the FBS skeleton. Which is why I asked if you could match the skeletons please
I can see if I can remove the extra bones, but from what I'm seeing in Blender the extra bones are also in the Animation files. Which Animation FBX zip are you using?
