I travel not infrequently with my wife and (adult) daughter. We are doing the same again tomorrow. The last few times I have flown, we have been unable to collect boarding cards online because for my daughter it says "The travel document details you have entered are not valid for this flight". There has been no issue at all at the airport. Once again, we have the same problem. Me and the wife have boarding cards, my daughter cannot get hers.

This includes flying UK to Gibraltar!

My daughter is in her early 20's and has a UK passport expiring in 2031. I have tried deleting all her advanced passenger information, even though it was correct, and inputting it again to no effect. What do I have to do on her account to make it work properly so that she can get a boarding card herself when she travels alone in just over a week? It doesn't seem to fit with any of the issues (VISA problems, old/incorrect passport data, selected for security check, etc.) I have seen on previous threads.