When the meshes are static they are lit correctly.
When I add cloth support to them they turn black with the same materials.
The meshes are exported as double-sided ones so I first thought that the two sides would be shadowing each other but even when I disable cast and receive shadow it does not change anything.
It is definitely a lighting issue as when I change the material to be unlit it works fine. Also when I remove the cloth component, it also works fine with the lit material.
I got same issues. Finally, I figure out vertices are too close in front and back face. I think you just duplicated mesh and reverse normal, so vertices of back face has the same position with front face.