I bought a round-trip, FC ticket (fare class "A") from IAD to to YVR. It was sold as a direct flight with a plane change in SFO. I'm flying on an A319 from IAD to SFO, and then switching to an A320 on the flight to YVR. The flight number remains the same.
I lost my seat assignments on both flights. When I hover my mouse over available seats in FC, I get a message offering to upgrade me for a fee -- one, of course, that I shouldn't have to pay. When I click on the available seat, the seat assignment does not stick, and I am returned to the opening page of my itinerary. When I called customer service, they politely told me there was nothing they could do and to please buzz off.
I am trying to get my hands on the last remaining aisle seat in FC, and it's kind of annoying to shell out the extra money and not be able to choose the seat -- let alone any seat -- in my ticketed cabin. My primary concern, however, is that the system doesn't recognize me as being in FC, and then I'll get to IAD and find that all seats in FC have been assigned. Then I'll be relegated to a middle seat in coach and told to take it up with WE-DONT-CARE later.
On my return flight out of YVR, I connect in DEN and have no difficulty selecting my seats in FC on both flights.