I may be tempting fate but I have flown quite a few of these "instant upgrade" fares in the last few years and they have always posted correctly for the fare class shown as purchased, either business of first. AA seem to be having a hard time with the post January 11 conversions and it possible that this has messed with current credits. I don't know whether you can get AA to look at what they reported to BA but that might be a productive approach.