Material Editor Viewport is Black Wehn Lit in Perspective View

My viewport in the Material Editor is black when in perspective view when lit. I have a light in the level, but didn’t think that would effect the Material editor. I’ve held down “L” and moved the light around with the right mouse button. When I let go of the mouse button the material will flash for half a second where I can see it and then black again. I created a new project and the same thing occurred. I’ve searched extensively for a solution to no avail. I’ve restarted my machine and that had no affect. Working with: UE 4.15, iMac 27-inch Late 2013, 3.2 GHz Intel Core i5, 8 GB 1600 MHz, NVIDIA GeForce GT 755M 1024 MB.

same issue here

I’v fiexed it verfiying engine version on launcher. Opening two projects and Saving one might caused this problem.