Mocap data not retargeting to Metahuman properly - what's wrong?

[nofarb17]

Hi folks:

I searched the forum and didn’t see anything close enough to my problem. I’m trying to retarget some mocap data I captured a few years ago. I applied that bvh data file to a DAZ3D figure in Blender and exported it as an fbx file. I was able to successfully import this fbx file into UE5.03:

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I then retargeted the data onto a Metahuman and got this result:

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When I play the level, the figure collapses onto the ground and lies there twitching (while the blender animated character is working well in the background):

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Here’s the IK rig mapping for the Blender character:

Here’s the IK rig mapping for the Metahuman:

Here’s the IK retargeter mapping from the Blender character to the Metahuman:

So, here’s what I want to know how to fix:

1. Why is the Metahuman animation (in the edit window) walking in place instead of
   translating across the screen like the Blender character?
2. Why won’t the Metahuman thighs bend at the waist, and why do the knees bend
   backwards?
3. Why does the character collapse in a heap on the ground during gameplay?

Thanks, Michael