Materials broken in scene view

I have run into an issue with a project where the materials/textures have broken in the scene view. Lightmapped objects appear with just the lightmap, unlightmapped objects appear with a lightmap on them which will change as the camera moves. The Albedo view is black, as is any other scene which does not contain lightmaps. Even stranger is the game view is working perfectly, as are other projects in the same unity version.

I have tried reimporting all, deleting the library folder, switching between standalone/webgl and back, switching from Dx11 to opengl, and now I'm all out of ideas. Any thoughts?

 

After all that I had a random but simple thought - close and reopen the scene view tab (bearing in mind that I had rebooted unity and my pc several times), and it fixed it! Phew! Would be interesting to know the cause.