Document Issue with Mobile App (iOS)
 

So I recently got a new passport. However when I have been trying to check-in using the mobile app on iOS it still has the old passport number on the reservation and then I can not check-in online.

I checked my profile on united.com

Home > My Account > Profile > Saved Travelers > Passports

There are no saved passports.

Anyone know if UA queries the Trusted Traveler DB using the Global Entry/Known Traveler Number to pull passport info?

I recently updated the information on the GOES website with my new passport and wondering if UA doesn't query in realtime hence it still has the old passport number.

No, Airlines do not have access to GOES only you and the Government.

I think what happened is that United is retaining the info from the last time they scanned your (old) passport. What happens if you save the new passport in your United profile?