Use default Mannequin animations with model from Blender

I am attempting to import a new mesh and use it with the default unreal skeleton and animations. I am using the Blender UE tools addon ([ADDON ] UE Tools - Community & Industry Discussion - Epic Developer Community Forums) but have also tried this with the regular blender .fbx addon (in several different versions.)

Here is my process:

  1. Generate the unreal rig inside blender from the UE tools addon
  2. Create a new mesh body, weight it to the Unreal rig
  3. Export the new body and rig with .fbx
  4. Import in unreal. It registers as a skeletal mesh, and I select the existing UE4_Mannequin_Skeleton
  5. Right Click > Edit model, model looks fine
  6. Switch to Animations tab. Animations start playing and the model is horribly mangled.

The rig seems to be totally twisted up. Bones are twisting on the wrong Axis or something. It is like this with all animations.

Since there are other import/export problems with blender, let me confirm that:

  1. I have already fixed the common Root Bone problem.
  2. I’m not having the common scaling problems.
  3. I’m not having the multiple root bones problem.
  4. My rotation axis is set correctly (my character is at the same orientation as the default mannequin, until I go into the animation tab. However, if I go into the Skeleton Tab and select the Root bone, it is set at 90 degrees on the X axis.)
  5. I have tried different export and import rotations, and none of them make any difference. The model is still mangled, and in exactly the same manner.
  6. All my bone names and hierarchies match.

I haven’t been able to find another example of people having this problem at all. Any help would be appreciated!