Does UE4 strip out the Static Mesh collision before exporting .fbx from engine?

I’ve been trying to convert some assets that I have in a newer project (4.24) to an older project (4.21). These static meshes have custom UCX meshes that were imported with them (4.24) to get around having to use the basic UE generated collision and they work fine in game. When I export the meshes to .fbx they dont have collision meshes with them at all anymore. No collision when I import to 4.21 or even importing back to 4.24. I have the collision box checked in the export setting and on import I have the auto generate collision setting off and the single convex hull setting off as well. Any help? I can’t get any answer on Reddit or the UE forum so I’m hoping someone can help here. Thanks in advance.