Seat assignments get dropped or changed frequently for many reasons. Schedule changes, even without a change in aircraft type. Schedule changes where the aircraft type is changed and then changed back. Heck, it happens even if you call to reprice an existing ticket if the fare decreased. Day of departure equipment swaps. And yes it can happen for W&B.
It’s impossible to really speculate why it happened. Contacting AA after the fact is not exceedingly likely to yield answers.
But what is generally true is that by the time you’ve boarded the plane it’s most likely too late to do anything about it. You said they selected the seats at check in. Did their boarding passes reflect the MCE seats? If so, it should be a pretty easy conversation with whoever informed them of their new seats (e.g. the GA), particularly on an emptier plane, to get those seats - or other MCE seats - back… and if they couldn’t because of W&B, they’d tell you.
Last edited by javabytes; Nov 26, 2022 at 12:22 pm