A couple thoughts re: this issue:

1. I have found that the AA seat map is far better to work with than the AS map for American flights if you are Gold. I reserved a (bad) seat initially using the AS site, then changed seats (no fee shown or needed) to get the preferred AA coach seat using their seat map. This was an award ticket - not sure if that makes a difference.

2. If my experience was typical, the AA customer service reps no zero (nothing) about how the AS Gold program is supposed to work. They can't even enter your AS Mileage plan number to get AS credit for paid tickets without multiple transfers to "supervisors" or "technical specialists". Expect to get the audio equivalent of "deer in the headlights".