After a million tries, and another billion fails, I finally made it to what seemed the end of the Clocktower. A horrible jump puzzle that I love, due to the difficulty (doesn’t seem other people do though).
As I was ready to leap into the hole that was made in the clock of the Clocktower, I reached inside, got the achievement and was ready to be teleported to my delicious chest of goodies. Though where it teleported me was not the delicious chest of goodies, but back to the lobby where you wait to join the match, afterwards I was instantly teleported in to play the Jumping Puzzle again.
I am unsure if you have a time limit in which you need to get that chest, or if this is a bug, but I presume the last.
Hopefully I don’t have to redo it, and I can give name, picture that I did actually complete the achievement as well as any other evidence that might help me get what I was tricked for.
Thank you very kindly!
Diabloste.