i have noticed that in 4.17.1 when you adjust lens space in oculus rift (button in the bottom of the headset) the screen goes black (but not suspend rift, guardian walls works for example) in packed game you can give rift image again presing alt+enter.

HI - Encountered this at work and I reported via UDN. Word from Epic is that this is a confirmed bug and will be fixed in 4.17.2 Cheers.