I’m using single files containing multiple meshes to organize source files and there are problems with updating the files. I make materials in Unreal editor and assign them to objects after they’ve been imported in, I don’t import materials from mesh files.
As example of the file structure: mesh_items.fbx contains meshes for crossbow_heavy and crossbow_light and several others. I import it in as uncombined mesh and get both meshes as separate objects, but it’s not possible to reimport (update) the meshes without running in to rather huge set of issues:
- If I select a mesh in content browser, right click and hit reimport, the meshes don’t actually get updated at all, they just flash and a success message pops up saying they were reimported.
- If I double click a mesh to open the detailed view of the mesh object and then select reimport behind the asset tab, same thing happens (nothing, but confirm that it worked)
- If I use import button in content browser to “override” the mesh_items.fbx that contains the meshes, it will reset all the materials on the objects BUT the meshes will update.
There isn’t this issue when using single meshes and completely ignoring the option to not combine meshes on import and reimporting works just fine, but the uncombined mesh import method is fairly flawed at the moment. One solution to comes in mind is to have container kind of object / folder in content browser that would represent uncombined mesh import, something to allow user to update whole root mesh or at least the submeshes inside it 
I guess this is partially a bug report, but not fully. It’s clear there is a weird functionality in the uncombined mesh asset pipeline, but it’s not necessarily “a bug”.