Wintersday JP bugged
Is it possible that you died the moment you landed inside the box? Happened to me at least twice.
Nope, health was just fine and nothing was killing me. I also had several guildies report the same thing, as well as another person in that instance’s map chat.
Unfortunately it’s not a bug it’s just client lag. You see yourself make the jump but due to lag the server registers you as falling off the edge thus returning you to the beginning. It’s happened to me countless times and the only solution is to try again.