We just ran into a bug where we can no longer see the scene art in the editor. Everything still appears in the Hierarchy window. All mesh renders are turned on, You can play the game and everything appears normal. You can create a build and everything shows up, The problem is in the Editor. I would not be surprised to find there was some setting that had been changed that disabled most of the rendering, but I am not aware of what it would be. We can see nothing in many levels and can see the NPCs in others. None of the normal scene art (walls, ceilings, floors, props, etc) is appearing. Any help would be greatly appreciated!
It turned out to be the layers had been set incorrectly.