I was flying today and on with LA Center just passing Las Vegas when I heard on 124.2 that SWA3641 did not have reliable airspeed or altitude information. I was on the sector for about 15 minutes while they were trying to figure out what to do through their company dispatch. It was at 0040Z and I'm not sure if there is coverage on LA Center but maybe Las Vegas Approach on their way back.
https://flightaware.com/live/flight/SWA3641