Guild Wars 2

My group took down that shaman boss where you can get the chest by keeping all of those prisoners alive. The chest appeared before the cut scene came up so i went over to loot it. as i was opening the chest the cut scene came up. after it finished i was no longer able to loot the chest like everyone else. nobody but me had the issue as i was the only one to try looting pre cut scene

same issue in here today, will not open it before again