One more thing @k9dr. They just refreshed the key system at Luxor, and they were having some problems.
I was never able to get the digital key (via MGM app) to work, but I was able to use the app for check-in and to get a physical key made at the self-service kiosk. That saved me a bunch of time compared to waiting in line for check-in, FYI.
Good to know - what time did you check in ??