Ok...I finally checked in at 12:50am PST.
However, when I tried at 12:48am, it was still givng me the same one of the flights was not open blah blah.... Then I went to manage my booking, using "Access Single Int" instead of full login, entered my CC#, got into "upgrade flight", cancelled without changing anything. Back out tried OLCI again....it worked. I know most likely it was just a coincidence because it is about time for the system to fully discard the old waiting list now....however, i wondered wether that Access Single Int with CC# fixed a messed up PNR....Just thought ppl can give this a try in the future should similar problem arises.
Either way, Im the #168 checked into AC29 - i guess way too late...