It seems like the FBX export of MH skeletons in 4.26.2 is broken somehow. I was trying to find a way to link up iClone to UE4 after seeing a few videos, and wasn’t having much success. I found this video in which the author actually ran right into this FBX issue I’m describing:
I was able to confirm the bug in my own local testing. No matter what FBX version I choose for export, and no matter what export options I choose in the dialog, it doesn’t seem to correct the issue. The hands are totally inverted/on the wrong side. Trying to animate this produces a mess of movement.
I even tested the FBX export in Blender and the bones look all wrong (even if you adjust axis orientation during import in Blender). It seems like the bone positions are getting translated wrong on the way out.