Since I started playing this game on release for PC I haven't turned in any of the gunsmith materials as I never looked into what they were used for and what NPC reputation was until today. I had read up on it and decided that I would now use my 1000+ gunsmith materials to acquire all of those engrams that I had built up. I opened them all and got the legendary items I wanted only to discover that the majority of the rewards had not gone into the postmasters inventory. Im guessing that this is probably down to the postmaster not having an overflow inventory. I also tried exiting the game and going back in but there was nothing to collect at the postmaster.