I have switched project to UE 5.1 and have this issue now. When I open any mesh it displays material as grey. Changing materials just chenges a bit greyness. In unlit mode it shows tekstures and is ok but in Lit all disappears.
On scene and thumbs it’s all ok. I have this problem in 5.1 version only
In case if someone has the same problem after converting project ffrom 5.0 to 5.1
What helped me was creating completely new project in 5.1 and then migrate there whole project having this problem. In new project all works perfectly fine 