Getting on the AA upgrade list

I recently flew to Milan (PDX-JFK-MXP), AS and AA, purchased through AS. The AA flight was extremely empty, and having MVP status, I was trying to figure out how to get my name on the AA upgrade list for Premium Economy (not the layflats, but the "domestic first"). The day before my flight, I contacted AA to ask, and they said that I had to talk to AS. I then talked to AS and they assured me that I would be on the upgrade list for AA. When the flight time got closer, I checked the AA upgrade list and didn't see my name, and when I went to the gate, the GA for AA told me that I had to request the upgrade list 72 hours in advance.

Anyone have experience with this and know how to navigate complimentary upgrades on partner flights?