Yeah that happens when you're out of tracking range of the camera, I know you said you tried sitting closer and further but the camera does need to be pretty far away to work properly, I can *just* about get away with ~4 feet, but 6 is much better. It could also be the bug that cropped up with the camera not turning on in the rift control panel, try going into the control panel and selecting "restart driver service", or something along those lines. I've not had this issue since updating the Oculus drivers, but I used to have to do this every time I started up my DK2.