I also have problems as an *SE out of YYZ and Canadian airports when checking bags on Aeroplan tickets. Agents/Concierges have told me that the "override" for no-bag fee as a SE no longer exists, suggesting that it's a "system bug" that IT doesn't have that as an option. Of course, out of a UA-handled airport, one benefit of their system is that they see my SE card, they give me 3 free bags
It's a *A-wide benefit that *G get free bags everywhere, so I don't think it's a sign of things to come... But I wonder why that option for free bags doesn't exist in the system.
In addition, it's hit or miss whether my *SE shows up on my boarding pass.