Hey, not sure if you’ve seen it, but there’s a free add-on you can use for vertex order. I haven’t tested it, but it should work.
But there are more issues here. As Mysfit said, something happens to the FBX during export — it corrupts the file and reshuffles the whole vertex order.
There is also one major problem with skinning (if you do get it to work): it distorts the joints, such as the wrists, knees, and legs, especially for bulky characters.
Here is something interesting: in the editor, it indicates that the actual size of the wrist is greater than the default value. Therefore, if the joints are set to the maximum value (as defined by the editor), and the conformed costume mesh skinning is smaller than the actual mesh, it leads to these deformations. This is likely because the deformation feature does not appear to support larger, wider, or more bulky characters. The system seems to interpret its own highest value as a limit—if you exceed that value, it simply applies the maximum setting rather than accommodating the actual required size.
