So I had a strange one two weeks ago.

Was on the RUC waitlist for outbound and return flights. The outbound cleared as a Complimentary upgrade just inside T-24h. The inbound cleared as a Cert Upgrade probably around T-18h or so.

It was good because I only burned 1 certificate (and that one was tight so I may not have made it as a complimentary).

So how did the complimentary one happen? Did they only release R inventory and not O? If so, do they reshuffle the upgrade list to ignore the priority UP2A (or whatever it is) since that would only apply for certificate upgrades?