I had this about a month ago on a MEX-DFW-PHL return of a paid F itinerary on AA metal that had included a US segment on the outbound. It took 10 minutes of furious typing by the ticket agent on check in at MEX to print the BPs. I could not OLCI, and the miles for the MEX-DFW segment still haven't posted - AA swears I wasn't on the flight. This thread reminds me I need to follow up on that.
I hadn't seen that message since paper ticket days.