This happened to me too. I've never NOT had pre-check until this past Thursday when I flew EWR - LAX. I noticed my mobile boarding pass didn't have pre-check, so I called and United said that the Known Traveler number is still in my profile, but sometimes TSA randomly doesn't issue pre-check. That's when I noticed that the Known Traveler number wasn't IN the reservation. I tried to add it on the app, but the number wouldn't save. At the check-in kiosk, I tried to add it, but the kiosk wouldn't take it either. The agent suggested that I go talk to the TSA Pre-Check desk on Level 2. She wouldn't help me because I received the Known Traveler number through Global Entry. I take the train over to Terminal B to talk to the Global Entry desk/room and they verified that my Known Traveler number is still valid. I go back to Terminal C and wait for 30 minutes to get through security arriving the gate at boarding time. The same situation occurred on the way back to EWR last night from SAN. I used Saver Award miles for the trip. I just checked my profile and it looks like my birthdate was changed by 11 years?!?!?
Has anyone else had a similar experience?