The imported 3D models are OK. However, after animated, this happens to the eyes:
It’s not a problem about translucency.
The eyes are almost outside the body, but just when animated. It’s a Mixamo character, and this happens only when we added a root.
We have two versions of this character, one is the enemy, original Mixamo model, without root. The animations works fine.
The other is the same model, but root is added in Blender and this problem happens. Weight painting is OK.
I guess there is some wrong setting on model or animation, but I don’t know if it’s some importing or export setting on Blender or Unreal.
P.S.: My real life eyes was like this after I found this bug was happening.