I just did an expedition, and because there was a lot of yellow loot lying on the ground I couldnt fit in my bags, i decided to go after it after I killed the boss, thats what the trade altar is for, isnt it?
I emptied my bags close to the portal, like I did several times before and went to have a look for the rest of the loot, only to find not only that despawned, but also the stuff I put besides the portal...