Me and my 2 friends lost ever single piece of loot and all the XP from 3 different missions out of 4 we played. One of them must of had like 6-8 lvl taken away from him... The other at least 2 lvls.....3 missions with full loot bags just gone, 10-15 relics/archo per a mission gone... Missed out on about 5 million credits reg loot, because the game just wants to take the progress and act like it didn't happen.... This is the first time it has happened to us, but I know I have other friends in the game that this has happen to as well... This is a game breaking bug.... It needs to be address ASAP before anything else. Spending hours doing mission with nothing to show for it, will make people just quit playing. 

Thinking about it and reading some of the other posts, The one mission that went through only had about a page of loot drop. Real light loot mission. The other missions where very loot heavy, as with me using high warp heat, we get champions by the dozens spawning in every minute. I run solo all the time and get loot like crazy and it never disappears, so this is something with heavy loot and coop.