Not sure how many times I have to say this or how to get people to comprehend, but it is likely connecting passengers moving to the top.

Connecting passengers trump all others, then it is status and fare class. The premise is that if you've started your journey with an upgrade it should carry all the way. It is good if you live in yow, but sucks if you start in yyz or yvr.

A good concierge will override on the international flights to push the SEs to the top, but by default a connecting E would be first.