Make sure, you're in an exact same point where a friend of mine got stuck.

Go again to the archer's guild, there is an NPC there in front of a door (you can't enter the door, it's behind him, but it's obvious he's guarding it.

Talk to the NPC, and tell him you want to enter the door (the NPC WON'T have any quest mark on his head), he'll say something about Festive Endeavours, which is the following quest), when you enter the door (mini instance) the next quest will be there.