Exporting MetaHumans questions

I’m trying to retarget some animations using MotionBuilder, but after a week I don’t seem to be getting anywhere.

First, when I originally downloaded my MetaHuman’s source file, I got m_med_nrw_body_rig.ma. When I thought I had mistakenly saved over the original file, I went back to download the source again but this time I got Wallace2_full_rig.mb, which seems more right since it has the head skeleton and textures, etc. But when right clicking in the Outliner in Maya it will, for some reason, delete every constraint in the outliner, so when I wasn’t sure if I had mistakenly saved over that file ( don’t worry, they’re being backed up now before opening in Maya) I went to download it again and I am back to m_med_nrw_body_rig.ma

So my questions are:

  1. WTF
  2. Which source file should I have, and if it isn’t the full rig, how can I make it the full rig? Because the other skeleton, again, doesn’t have the head along with a lot of other things, so the full rig seems to be more what I need/want. Well, actually, obviously it is because the source doesn’t help me or anyone else without being able to animate the head. So, how can I get the full rig back as the source that is exported?

Once I exported either the full rig or body skeleton into Maya, I ‘sent’ it to MotionBuilder where I set up my retargeting. No problems, both retargeted fine, although to get it work I have to use the Driver Skeleton, which I guess makes sense in that it is driving the actual skeleton. But then when I export back to UE, it thinks I have changed the name of the skeleton or inserted bones so I get this:

The Skeleton metahuman_base_skel, is missing bones that SkeletalMesh wallace_SH_2_retargeted_Maya_source needs. They will be added now. Please save the Skeleton!

I also get errors about weighting for other skeletons or meshes having changed and do I want to updatethem. Whether I choose yes or no, I get the same result and that is actually no result. The animations don’t work, my MetaHuman looks like all of his weights are off kilter and even the bones get wonky (attached image); it looks to me like UE is using the animation from the source skeleton in MB instead of the animation from the retargeted skeleton and squishing it down to the MetaHuman skeleton. Edit- actually, its the m_med_nrw_animbp that is making the skeleton wonky, as disabling it gets everything back to normal. I also don’t see what that animBP is even doing; it looks empty, and there isn’t anything I can see that you could change if you wanted to.

So 3., is there any documentation or are there any videos that anyone is aware of that have the body skeleton workflow details? I’ve seen one for the facial structure that looks like it comes from someone with early access to all this, but not one for the body (and that face one wasn’t going to MotionBuilder, so its only partially applicable).