Originally Posted by Salomon82

I also managed to upgrade my return flight from Europe to Asia.
Called up the hotline, and the agent obviously could not confirm upgrade availability without a ticket number. Booked the flight on priceline with 24h cancellation guarantee. It's a shame, as with priceline you can't choose the booking class, and I would have gladly paid $100 or so more for a higher booking class in the return leg (btw, matrix doesn't seem to work either).

Some data points in case they are helpful:
Outward availability before // after upgrade: J4, I1 // J3, I0
Return availability before // after upgrade: J4, I4 // J4, I4