That is a problem at outstations and I wonder how/if this even works for the waitlist and T-24 clearing... since at AMS they take control of the ticket and don't have upgrade/waitlists so I would think that anyone who used a GUC for Y->PS is not going to get upgraded in AMS unless you happen to get there early enough and run to the transfer desk like pax used to have to do when trying to upgrade into an open J seat with cash or a cert.