So today, I used the random group finder... 2 hours of waiting and ended up as DPS in a Cradle of Shadows group. Ends up though, that I'm not actually in the group when I enter the dungeon. I thought I'd been kicked, but apparently I was not part of the original group - and their fourth couldn't get in because the instance was full (because of me). I proceeded to stay in the dungeon with that 3 and RUN the entire dungeon, groupless, and completed it. Didn't get random group credit (obviously)...
How is this even possible? Just another Zenimax bug?