Since quite some time ago, there's a bug in the editor where the scene view stops updating while you're flying around with the camera. Steps to reproduce: Press and hold the right mouse button. Press and hold the shift key. Press and hold the W key. The camera will start flying. Don't move the mouse, not even one pixel! Keep flying. After a couple of seconds, the scene view stops updating until you move the mouse or release any of the keys. If it doesn't happen, try again various times. Note that the camera will still continue to fly, but you won't see it, because the scene view isn't rendered. I already filed a bug report, but they said they couldn't reproduce it. Can you?