I was able to change my seats early on at AZ. Then I went to AF to select my seat, but then I couldn’t do any seats changes on AZ anymore. I assume this is a pretty common problem and chalked it up to IT. Have not thought much of it as everything is OK to fly.
As to downgrading at check in, wouldn’t that require a special flag on the reservation or our booking class to be revised? I assume we would simply show as being booked in business to the check in counter unless they went digging into the fare rules or was otherwise alerted? To my knowledge I was advertised and booked a business class ticket, I would be very angry should they tell me the day of I am being downgraded to Economy.