Originally Posted by FlightDetective

Not sure if this is why, but I was originally on the BA codeshare that is AA1 for a flight in a week or so time. A couple of months ago I got a schedule change and I was moved to the AA171 at 6am instead. I was baffled, because AA1 is operating according to AA. However, I've since checked by booking a dummy one way for my flights and there is no BA codeshare on AA1 for my dates. Every other flight is available except AA1. I was like you, looking forward to taking flight 1, but it was not to be. Not sure why the codeshare has been removed, but that might be why you can't do it, just a random data point.