?????? is clearly American's new way to add fun to flying today. If they simply put "Upgrade requested" or "Confirmed" you'd be on your way and we wouldn't have a thread to break up the monotony of boarding priority and lounge posts but ??????? (not just one but a whole series of question marks) keeps you engaged so that you'll keep checking your itinerary.
While the ???????? display issue is an IT problem, did the phone agent say that you were added to the upgrade list for the segment? It certainly is odd that only one segment would have that issue.
Enjoy the trip; it's a beautiful country!