Well for domestics it always worked out but this was actually the first time it worked for the TATL part, too. Before I either got a blank screen or "Please contact an agent".
Did you have your passport details stored? I have been using OLCI exclusively and never once used a check-in agent in 5 years and 5-600 flights. I am shocked you have gone this long...it can add 30-45 mins to every flight. Congrats.