Unity Editor is very dark black after updating to 2018.1.8f1

We are in the process of trying to migrate our project from 5.6.1f1 to 2018.1.8f1 and noticed that the editor loads almost completely black (see attached). I've gone through and removed as many of the shaders as I can to just the ones being used by materials in our project to no improvement. I'm assuming it's one of these shaders and the only thing I can think of is to just delete all of the remaining ones and then if the problem goes away slowly add them back one at a time. But if anyone has any other suggestions I'd love to hear them.

 

I made a branch in git and just started deleting a shader, exiting Unity and reopening the project until I found the one that was causing the trouble. It was Shaders/BuiltIn/DefaultResources/Internal-GUITextureClip.shader