Happened to me last week. Was out on a drive and when I reversed, I didn't get any of the rear camera guide lines. So I did a reset of the vehicle. When it came back on, I had blank screens. I started driving and they soon populated. Not sure if it was a delay to the reset or what but I haven't...
Picked up my R1T lease on 12/30 and had this issue start showing up shortly after. Mobile service did come out and check the connectors in the gear tunnel door and under the bed as well. One or two were potentially loose and were reseated but the issue has persisted. The alert comes and goes...