I wonder if this has anything to do with it being the 'wrong' PNR. In the past when I've booked Iberia flights with BA, I've been sent the 'marketing PNR' but not the actual 'operating PNR' for the Iberia flights. Although my bookings contained both BA and IB metal (the marketing PNR worked for the BA flights only).

Personally I'd phone BA and ask if they have another PNR number for this booking.