Had this problem for about a 3-day period SFO-SAO -
it was a relatively last minute work trip and I could never get AA to price out a dang itinerary - it always gave the message "no longer available" - thru clicking all the flights. Same problem each day.

In the end, had to go with *A flights as our funders just needed an itinerary with a price tag on it to approve the flight.Was hoping to make the transition back to OW!