Trying to checkin online today for a flight tomorrow. I'm assigned seat 8C but web checkin keeps assigning 27C. Called reservations but they don't know what's wrong.

So:
A) If I show up at the airport and use the kiosk will I have the same problem?
B) Am I stuck waiting at the desk to resolve this?...I have no luggage and hate to have to get to the airport early just for this.
C) The flight's oversold...if I check in too late do I risk getting IDB'd...I don't have status with AS. I'd rather have an assigned aisle seat at the back than a middle seat or no seat at all.

Thanks!