Mods, please feel free to merge this into another thread if appropriate. I could not find one which covered this exact scenario.

I flew yesterday on an itinerary with one international segment connecting to two domestic segments. At time of booking I requested an upgrade of the entire itinerary using a GPU. The international and second domestic segments cleared immediately (as I knew they would because there was R availability).

The first domestic segment was waitlisted, the itinerary showing "Upgrade requested". By T-25 there was one empty seat in F remaining.

At T-24, the upgrade had not cleared and the indication then changed from "Upgrade requested" to "Complimentary Upgrade Requested". At the same time, the empty F seat disappeared off the seatmap, so I assumed that someone else had taken it and that I might be out of luck.

Having done OLCI, I then looked at the waitlist via the mobile app and saw that I was not on it at all. I phoned in and was told "We can't see you on any list and there is nothing we can do". This mantra was repeated when I called back (several times, in case I had just had an incompetent agent).

On checking in at the airport for the international segment, I asked the agent to have a look at that first domestic segment, and she told me that I was now # 2 on the list.

When I arrived in the US and went to the gate for the first domestic segment I was now # 7 on the list. Needless to say, none of those on the list got an upgrade.

While I realize that probably someone else did beat me to the last remaining F seat, I wonder if this is another glitch in SHARES. Did the system make a mistake in changing my GPU from an instrument-backed upgrade request to a CPU, and if it had not, would I have been luckier?