I’ve created a Static Mesh and edited it on Modeling Mode, so it uses 2 diferente materials. When I converted it to a Skelleton Mesh with the Skeletal Mesh Editing Tools Plugin, only one of the materials show. How can I make so both materials show?
Static Mesh:
Skeletal Mesh:
I have the same issue and cannot find an answer anywhere. This is the first mention of it on the internet I can find. If someone knows why this happens when converting static mesh with multiple material slots to skeletal mesh, please reply 
The skeletal mesh still shows there are 2 material slots, but does not display then in the editor
Have also been dealing with this problem and have been trying to find an answer with no luck. But for whatever reason clicking through one of the tabs under ‘skin’ while in the skeletal mesh editor seems to have repopulated my other materials. Before in asset details panel under sections, I only had the base material, but now it’s showing all 3. I don’t know if this is a bug or what.
