I just reported the issue using the in game support, but I would like to write here as well. I have completed the triple trouble event 5 times already getting gold medal. All 5 times I got just 1 box (at the wp) with crappy loot, similar to Behemoth but without any side box (standard box you get at the right side of your screen and the gives you a rare or an exotic).
Some ppl are talking about an achievement box, I saw friends or videos online that ppl dropping many adventurer bags from the big box and 2 boxes on the side. I am only getting 1 big box at the end with green loot and maybe a rare.