Found another bug on mac osx 10.10.5.
After adding a jump pad in the editor into a custom map, the 3d viewport turns black and just shows black. The other viewports are unaffected. Have to remove jump pad, save map, open a different map and then reopen the map I was working on to see 3d perspective view objects again.!
Removing the jump pad and rebuilding returns the 3d viewport to working properly.
Version: 4.8.0-2710036+++depot+UE4-UT-Releases