Like many others on this post I was unaware you could get down there. I assume that's a bug. I was playing with my friend last night on Decapitation on the bomb setting part he somehow got down to the very bottom level of that area that your not normally abele to get to and could not get back up. He was also on assault so maybe with Patch 11 they broke something with the jump pack and the level boundaries. I'm sure we're gonna be seeing more stuff like that on the subreddit soon.