Material Slot Names Get Replaced With "None" After Merge Actors Operation

After merging two actors the resulting merged actor's slot names will be replaced with "none".

Fixing this is a very tedious process for our licensee since there usually is a large amount of slot names to get to.

1. Open a blank project
2. Import both attached FBX assets (make sure combine meshes and import materials is checked)
3. Open both assets and look at the slot names they should all have unique slot names
4. Drag both meshes into the scene and select both > right click > merge actors > default settings
5. Open the resulting merged actor

RESULT
All of the slot names have been replaced by "none". The sections "material ID" assignation are wrong, there is no more black or red material

EXPECTED
The slot names are preserved. The sections point on the correct material id