Roll back on realm affecting random members, not everyone

This has happened 3 times now over the past couple of days. I play for a length of time, log off. then the next day when i go back into the game, I have lost time (anywhere from 30 mins up to a couple of hours), the game has rolled back for me. This has happened to two or three others also. It seems random - it doesn't happen when I play for just a short time, save & quit, and come back. I have 'lost' significant amounts of in-game work thanks to this - well, not lost exactly, as it's like I have never done it in the first place, even though I did. Getting frustrating, hoping there's a fix.