I passed the last 8 hours trying to fix this issue.
I animated a combat scene into Cinema4D (rigged with ActorCore), everything looks perfect into Cinema.
Unfortunately, I mistakenly decided to animate before uvmapping and texturing, well…
I had in mind to export the animation using .fbx file format and adapt it to my UV mapped and textured mesh, but whenever I import into Unreal, it suddenly breaks the mesh.
The trouble may be leaf bones (in Cinema4D they are null objects) but i could not figure it out.
Since I spend 2 weeks animating it would be wonderful to get a solution.
Everything i tried so far:
1: Transfer correct UV to the animated mesh, and tried to export via alembic or Cineware (Uv broke, but it kept the animation perfect)
2: Remove and adjust weight from null bones to joint bones (Breaks animation and it was way too tedious)
3: Use VAMP to transfer weights and/or UVs (breaks everything)
4: Retargeted into Cinema4D using Character definition tag and Solver (breaks animation into Cinema)
5: Used motion clips into Cinema4D to bring them into my adjusted model (breaks animation into cinema)
6: Export the animated joints only and adapt them to my skeletal mesh into Unreal (Breaks basically the whole animation)
7: Import into Blender and then into Unreal (breaks into blender in a similar way as Unreal does, but not the same)
If you have something in mind please share, I don’t want to waste 2 weeks 
In the screenshots:
Anim pose into Cinema that works perfectly
Anim into Unreal that breaks (maybe the leaf/null bones)
My correct model
