We just upgraded today. We had 4 day PHs with MP purchased from UCT. No issues at all using the UCT tickets. We went to the Halloween party last night, so wanted to wait until that was over before upgrading, and I thought based on some reports here that later at night, the tickets windows would be slow. Last night we went out after 10pm, and there were long lines at the ticket windows. The app said “upgrade your ticket” but when I clicked it, it would not apply my current ticket. When I clicked my ticket, it said it might be eligible for upgrade but I had to visit the window to do it (I know in June when we went, I bough PHs with MP directly from Disney, and I was able to upgrade in the app and it did apply my ticket costs, but we decided not to upgrade at that time...). So I went back to the booths at 7am this morning. No lines. Still took about 40 minutes, and we were not doing a payment plan. They would not give me my DHs or DDs without them being physically present at the window, so I had to wake my child up after the party night to do this. Not what I was hoping for, but we had a flight to catch today to go home, so it had to be done. Could not do it earlier in the trip because the days were reservation only and were booked up for at least one park (we did Friday-Monday, and only Monday was good to go).
There was a lot of writing, getting a supervisor, printer malfunctioning, printing on wrong side of plastic pass, etc. And this lady said she had worked there for decades and is a trainer for GS. She did change our expiration date from one year from today to one year from day of first use of the tickets we were upgrading, which I expected. We did get gate value for our UCT tickets, so that saved about $90 between the 3 of us. Definitely took a very long time.