Recently had than on a domestic trip. Very weird. I noticed on the web app that the KTN was blank when checking in. Rather than look it up, I decided to see if the mobile app would be the same. It was not. It had the KTN and got Pre with no issue on the mobile app. I'm 100% sure that had I continued with the web app, I would not have received Pre. I think this is an issue on the UA side.

I also had my first ever SSSS and of course no Pre a week earlier on a MUC-SFO trip. I had to go to the ticketing counter as I couldn't the mobile or web app to check in, which sounds like SOP for SSSS. I'm going to say this was likely (hopefully) completely random as I have not have any issues that might revoked my GE or Pre.