Description: Emergency guild quest popped up and the goal was to kill 'Sabranak' in Howling Glacier, so I picked the quest and joined a raid, arrived there at 20% left, interacted with the BAM for the last 20% (as in dealt damage and received some as well), and after it died our quest remained 0/1.
Server: Mystel
Screenshot: 
Additional Information: We did this quest two times ago since the update that came along with 'Rise of the warrior'. First time I joined a raid with one guildie and we both attacked the boss till it died, then after it it said in the guild notices that only my guildie advanced the quest (1/1).
The second time was 4 of us and just made our own raid and all went there and attacked the boss till it died, this time it said that all 4 of us advanced the quest (1/1). So how does that work? Is there some 'hidden' condition that a member must meet in order to advance this quest? Or is it just a bug?