No loot from Tri-key Chest
I don’t really have a solution, but you aren’t the only person this has happened to. I figured I’d post a reply since no one had yet.
Something similar happened to a friend of mine regarding the CoF Daily Bonus Chest. When he clicked on it, the icon did the open animation, but nothing popped up to loot. He, too, tried relogging and the chest was gone with no badges to be found from it.
I assume it is a new bug, but if other people are missing out on loot as well, hopefully ANET does something about it. Sorry to hear you are having issues with the chests too. I know how disappointing that can be
File a bug report and they may be able to a least get your key back.