So, when I was exploring the cosmodrome I mapped what I call my "loot run". I found some of the loot chests spawn spots (usually in caves, and on cliff ledges/ridges), It started at the beginning spot of the map and went through the airplane boneyard (sorry forgot the region names) and ended in the boat yard. There was one region I explored outside of that where the fallen and hive aliens fought eachother (the hive aliens would walk up the hill to fight the fallen). At the end of the region theres a building on your right with some fallen that spawn in that spot and past that theres a chain link fence. I saw a loot chest spawn in that area but no matter what my friend or I did we couldn't reach it, it was like an invisible box we couldn't enter even if we tried jumping down from above it. The only way we could reach it was if it spawned outside that little area, which didn't seem to happen as often. Hope this helps.