I have a model that is rigged and animated in Maya using multiple joint chains on different hierarchies, i.e. the arm joints are separate from the fingers and clavicle, which is separate from the spine, etc. All of these chains are skinned to the same mesh. When I export a .fbx, I select my geometry and the root joint of each chain and set it to bake out all animation. The .fbx seems to animate fine in 3D Builder, but when uploaded to Sketchfab, I get the problem you see below. It seems that Sketchfab only recognizes one joint chain and its associated skinning when it comes to animations, disregarding all others.
Is there any way to work around or fix this limitation, or do I absolutely have to use only a single joint chain for animations?