Guild Wars 2

Killed all the chak in the pit in Roots of Terror, even had the qualification icon on my buff bar. Got no achievement.

Were you in the instance with someone else? If so, it is possible you did not tag enough for kill credit. This happened to me and a friend so we had to re-do it and I let him tag everything first before I helped him kill them. That way we were sure he was getting credit for each kill. There should be enough in there to have about 5-6 left alive when you get the achievement.

Nope, I was alone. =/

I did manage to get it later though when someone helped me o.o