Originally Posted by
Blank Sheet
Yes, is my experience. Once you are checked in, your locked out of EUA. Only a TA or GA can issue the upgrade at that point or you have to be un-check'd in to allow another source to upgrade you.
Not to throw a wrench into this theroy because I'd love to know as much as the next guy how this works BUT I was flying TPA to DTW last November. I did OLCI at 23:59. I didn't get upgraded and printed my "coach" boarding pass. 3 hours later I went back to look at my reservation to see what gate I would be arriving into and there it was, my seat in "First." I reprinted the boarding pass with the new seat. Before reprinting I did NOT attempt to recheck in for my flight I just saw the change under my reservation. Now that is the only time that has EVER happened to me but it did happen.