This isn't normal. There seems to be a mismatch between what you booked through BA and what AA sees. After it's fixed, you should call AA and ask them to check carefully that they can see a reservation for each segment and an attached properly ticketed (probably reissued) matching flight coupon for each segment.

You might want to check whether there has been a schedule change (only a minute can cause problems) or change of flight number since you booked. That could explain why a segment has apparently disappeared.