Import the attach skeletal mesh, set the second material slot to use the first material then export the asset.
Open the exported asset in a DCC and verify if the materials are set properly.
Result there will be a material name Fbx_Default_Material_1 for the second material
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-205483 in the post.
| 0 |
| Component | UE - Editor - Content Pipeline - Import and Export |
|---|---|
| Affects Versions | 5.4 |
| Target Fix | 5.5 |
| Fix Commit | 32701938 |
|---|
| Created | Jan 31, 2024 |
|---|---|
| Resolved | Apr 25, 2024 |
| Updated | Apr 30, 2024 |