Has anyone else experienced major problems getting credited automatically for your flights between SEA and YVR?

I fly this route a lot and 75% of the time I have to phone in to get the 500 miles credit. 3 of the last 4 flights I have taken in the past 12 months have not credited automatically.

My fear is that, because United manages the check-in and boarding process (where they keep the big portion of your boarding pass) that his isn't an anomoly.

Flights from YVR to SEA are always fine. AC JAZZ is the operator.