Seems so, although my current itinerary also is an open jaw, so it's difficult to tell which is the cause of my "lack of upgradeableness" in MMB. I have 2 BA segments and 3 AA. I think this combo also caused my booking to get "tagged" in some way in the system - I had to queue uncecessarily for an hour to check in at LHR on Monday, only to find out that there wasn't anything specifically "wrong" with my booking. I then also got singled out at the gate for a full pat down and delay in getting on the bus at A10 . I wasn't a happy bunny by the time I settled into my Y seat on a fully packed 747