yeah, there’s lots of things that can go wrong when importing/exporting 3D models.
looking at your file, i see tons of nodes that aren’t related to the actual geometry or skeleton structure.
i would recommend removing everything from the scene except the model geometry, materials, and the skeleton.
try exporting and see if it comes out better.
from there, you can add things back, bit by bit, and see what is causing the problems.
for what it’s worth, the library we use to load 3d models has been updated, and the rat loads much better in the newer version.
however there are still issues.