Join Date: Jul 2002
Location: Still going through ORD security when boarding has already started
Programs: AA EXP, UA Silver, HH Gold, Bonvoy Gold, IHG Plat, Hyatt Disco, Reno Air MEGA Platinum
Posts: 10,311
Just following up on this in case it happens to anyone else.
So taking FTers advice, I called DL before I went to the airport, and they said everything looked fine, and the reason I couldn't check in was because of the Infant in Arms.
Unfortunately at the DL counter, it wasn't so simple. The check-in agent couldn't figure out what was wrong and ended up having to call the help desk, and the help desk ended up having to completely reissue the ticket. The whole thing took over 30 minutes, which was annoying, but I anticipated this and left plenty of time, so it was not a huge deal (other than making the lounge visit a bit rushed).
The agent (who was very nice throughout the process) advised that it was better to not attempt any online check-in at all if there is an infant in arms on the PNR.
Sure enough, I took her advice on the return (which was a different PNR but booked at the same time), and check-in took less than 5 minutes.