Guild Wars 2

So me and some guildmates jsut cleared CoF path 3 (Hunting the new Tribune) and we didn’t get the Dungeon completion thing.
No achievement update, no “Congratulations” and no 15 signets….
Another guildie told us to run around in the dungeon a bit, we did, nothing happened, we also stood around randomly staring at the screen for a bit, nothing…. And yes, I’m sure we completed the dungeon since the gu was most certainly the end boss, the NPC we ran around with acted as if we killed the end boss, and the right hand corner quest thingy didn’t update to something new.
When we tried to zone out and back in, the dungeon had reset completely (which i heard isnt supposed to happen that easily if you’ve not finished a path compeltely?But we didn’t get the credit/congratulations!)
Is this common? Do we have to worry about that each time we do a dungeon?

Keep the NPC out of combat on the last boss, it seems to bug out when she dies/ is dead for when the quest is supposed to finish.