#1 - Aug. 25, 2014, 12:42 p.m.
At the start of the instance the 3rd mob you face is the problem.
Mob: http://imgur.com/aEREdfl,EID1j8a,DNz7ZuE#0
It's not necessarily this mob, but after killing one of these mobs I noticed we were still in combat. There are four (4) of these guys in these locations. (Marked with yellow)
http://imgur.com/aEREdfl,EID1j8a,DNz7ZuE#1
After we went and killed another one of the groups we were suddenly out of combat. So all I can say, from what I saw here, is something about these mobs are causing the issue. It may change which ones depending on if you go left or right but they are the issue. For dev testing if you don't know a bunch of groups will avoid these mobs by just hugging the wall and walking past them. It seems this might possibly be an issue due to maybe the chained guys that won't attack on their own recognize your presence and aggro in essence but never attack or change so you never know it and then are stuck in combat.
Combat Bug #2:
Here is the map of where the next issue is. (Marked with yellow)
http://imgur.com/aEREdfl,EID1j8a,DNz7ZuE#2
The smaller yellow markers I believe are in error. These are the little non-elite spiders that you pull, but it seems the actual issue is after you fight the bigger spiders right before you head to bridge to boss.
Groups will usually kill one group and ignore other so after killing the first spiders and noticing now stuck in combat we killed the 2nd group as well but was still stuck in combat. So I can't confirm which mob is actually bugging and aggroing and causing the combat issue, but I do know something goes wrong somewhere after you fight any of these spiders.
I, and I'm sure others, have submitted bug reports on this but hopefully this will be more useful with images and actual testing done to show you where exactly on the map and in the dungeon the problems arise.