Not entirely sure this is eupgrade related but not sure where else it belongs.
I'm on AC991 YYZ-MEX tomorrow (July 21). When I checked in this morning at T-23, the app was showing 6/16 booked, 3 checked in, and 0 on the waitlist. A few hours later, it's now showing 15/16 booked, 3 checked in, and 2 on the waitlist.
What's the most plausible explanation for what happened? Selling 9 J tickets this close to departure seems unlikely. Maybe reaccommodating passengers affected by IRROPS, but the other YYZ-MEX and YUL-MEX flights for today and tomorrow are operating normally. A bunch of LMUs? Or a long eupgrade waitlist clearing and some bug preventing it from showing up in the app?