Since the migration, I have been able to select/change seats on an ae booking, for AC metal flights. At least I can still see the seat map, and attempt to select/change seats, it just gave a message cannot select seats.

Yesterday on AC.com trying to look at that booking, it gave a message my last segments SYD-YYZ have been re-scheduled. I looked at the flights and times, everything's still the same, but it won't allow me to go anywhere else, cannot display any other legs. Today it's back to being able to see all the flights (no more message of re-scheduling), can see AC metal seat maps, just still cannot change seats.

The trip is Jan. 1. But maybe it's true AC enhanced it, no more seat selection/changes.