As expected this has been taken down again.. Whoever is developing this functionality for Aegean has now, accidentally, put this live a few times before it should have been. Quite sloppy work and it may explain why the functionality didn't work so far.

Though, having said that, for me it did show one of my bookings eligible. That was a K-Flex fare that did not have I-class availability. I've not actually tried putting in the upgrade though, as I was expecting the function to be removed again - and I would not want to screw up my booking in some way. Without knowing how the upgrade standby list is processed there is little use in requesting an upgrade, especially if there are chances that it will impact your ability to change that Flex flight without paying the 23 euro fee.