I'm having the same problem - first fight is this Sunday and still showing "no seats". 3 flights codeshare operated by IB, 4th operated by BA and can select a seat.
BA say they can't help and Iberia has long phone waits.
Happy to "suck it up" as there are no awful seats in CE (although row 1 would have been nice), but did anybody manage to solve this or will it be most likely resolved at the airport?