Call me crazy...
Not literally (before you all do :) )! I sent my Rift S back for refund as it just wouldn't 'play nice' - flashes, wouldn't start up without multiple restarts of the software or reboots of the PC. ...
Forum Discussion
For me it's almost subliminal....blink and you'll probably miss it. I see one maybe once every two or three hours, sometimes never in a long session.