FBX naming conflicts causing collision to not import correctly.

For our static mesh pipeline we have group nodes in Maya that use the name of the asset. Under that we have a mesh that also has the name of the asset. We may also have collision as well so a typical asset would look like this:

• MyAsset (this is a group node)

• MyAsset (this is a mesh)
• UCX_MyAsset (this is the collision mesh)

I have attached [Link Removed] with this layout in the repro section.

Our exporter exports this asset to FBX and then we import that into Unreal.

In 5.4 this asset used the legacy FBX importer and it worked fine (both with combining meshes and not combining). The static mesh would import and it would have the collision from the file.

In 5.5, we're using Interchange now and when we try importing the same mesh, it renames the mesh to MyAsset1. Now since the mesh name is changed the collision doesn't recognize it so it either imports them as separate sub-meshes in the same static mesh if we use combine mesh, or as separate static meshes if we don't use combine mesh.

I tracked down the issue to FbxAPI.cpp -> FFbxParser::EnsureNodeNameAreValid on line 328. In this code it checks all objects in the FBX file and ensures names are unique. I got around this issue with the change to that function in the attached txt file [see [Link Removed] ] (too long for posting here).

Basically the change gets around the problem by changing group node names and adding "_Group" during import. It's not perfect but it seems to work as we've tested it with multiple imports and everything seems fine with the mesh and the collision. Note that the change does bypass skeletal meshes as those didn't seem to have the same issue.

I'm posting this here both in case anyone else is having this issue, and I'd like to know if there are any official fixes in the works for this. This asset export pipeline is quite common in my experience so I feel like it should be supported.

Steps to Reproduce

Export an fbx from maya that follows this format:

• MyAsset (this is a group node)

• MyAsset (this is a mesh)
• UCX_MyAsset (this is the collision mesh)

Import that asset in Unreal 5.4 - it works fine

Import that asset in Unreal 5.5 using Interchange and the mesh name changes to MyAsset1 and collision is broken.