Interesting one tonight. AC854, #2 on the J list, booked 39/40 so I don’t clear. Take my PE seat, when announcement is made about boarding complete, look at the app and there are 2 no shows. Ask the GA standing at the boarding door, she goes and asks and I am told no, the flight is closed. I reply that they are not supposed to do that until they clear the upgrade list. I’m told that a manager will come and explain it to me. After a few minutes, I’m told that they will re-open the flight and process the upgrades. Myself and another person got upgraded as a result. Always pays to check and ask I guess.