'Play' Mode suddenly only shows black

I am having a problem where upon pressing play I am only seeing black on the Oculus Headset, and although the scene is playing in scene view nothing, not even input is working. I have tried to 'undo' changes which I made before such event happened but even undoing the black screen persists.

This has happened on more than one project. Weirdly if I build the project and run the build it is fine.

Bug? Or am I doing something wrong?