Switching between PBR shading and Matcap - I need to turn of layers and paint every time


I’m sure I’m doing something wrong, but if I switch from PBR shading to Matcap my model turns black, and I need to select all, paint them using one of the materials that’s selectable when using Matcap. But not all objects are painted, and I have to select them an turn of a layer that has some paint on it, and then paint the object again.

I must be doing something wrong, as I thought that Matcap overwrites everything, all materials.