Since most of my travel is paid by work I rarely use my miles for tickets, more for upgrades, etc., so in a sense I'm kind of a newbe at this, but recently I wanted a friend to visit my hometown for Thanksgiving, so I redeemed a bunch of miles for J class awards to/from SCL for him, while I was on a paid ticket. The flights to the US went without a hitch. For the return we were on a paid flight from DEN to ORD, and then connected to our original flights back to SCL later that day; in the early morning we checked in at DEN for both our flight to ORD as well as our continuing flights on a separate reservations from ORD to SCL, had our bags ticketed all the way to SCL and were issued BPs for all flights. Once in ORD, he checked the AA app and couldn't find his ORD-MIA-SCL flights, even though he had physical BPs in hand. When we checked at the desk in the ORD AC, we were told that his entire reservation had "disappeared." Of course, he was reaccommodated almost immediately so everything worked out. At this point I was glad that he's new to travel, so he was constantly checking his reservation on the app, otherwise there would have been a lot of trouble when he tried to board his flight to MIA and I would have been on my flight to JFK and unable to help. My question is why his reservation would have "disappeared," as the AAngel put it in the AC, after he was checked in? I vaguely remember reading about something like this years ago, but I haven't seen anything recently about a similar experience. Any ideas why this happened? Did the system miss his check-in in DEN, and then at the 120-minute mark consider him a no-show? I would think that if the system had printed the BPs in DEN, it would know he was checked in. Any thoughts?