Thunderhead Keep Mission Bugged?

Last night I was trying to do the THK mission with heros and at the part where we have to defend the fort, there was only one group of mobs standing by the fort. After killing them, I went back towards the fort to wait. After roughly 20 minutes of standing there and nothing happening I walked around to see where the other mobs were but couldn't find them. I waited for another 20 minutes and still nothing so ended up resigning.

Any ideas what went wrong?

(I dont really remember).... But dont you need to talk to the King at the "top center" of the fort?

Talked to him too when I went for the walk around the area. Nothing happened.

Iirc, very rarely, for some reason the mobs don't spawn properly. I think you can force them to spawn by leaving the fort and approaching the portal, but not sure.

Resigning was probably the best option

If you successfully completed the bonus some mobs get stuck fighting the bonus dwarfs in the small 6 man outposts on either side of the gates.