Indeed. I wasn't able to get a confirmed seat at the check-in counter. Ended up approaching the gate agent who said "no, flight is completely full". When I told her I could see from the standby list on the app that J was only half booked and that I had requested an e-up on my confirmed flight (which had not and was unlikely to be cleared) she said "well I can put you on standby". My name showed up almost immediately on the upgrade list (last) and within a few minutes I was called with the others to collect my boarding pass. Thanks to all who responded.