I checked my seeker expedition after completing my own expedition and was rewarded with 5 pistols but didnt have enough room in my inventory for them. It appears that the only one that I actually wanted (only one with frost damage) as I could craft it was on the far right of the rewards lineup and when I went through all my popups for rewards, I went to sell the other worthless pistols I had gotten from the reward and noticed there was only 1 pistol on the ground and that none of the pistols in my inventory or in my buy back had frost damage and there were only 4 pistols with ilvl 151 between my inventory and my buyback screen, One of those 151 pistols had just been quality crafted and from a popup after the pistol reward popup. I also know that some of my other rewards were deleted since as a consolation for not successfully completing a seeker expedition, I got 3+ blues and there were only 2 on the ground and none in my inventory.