I never picked up 5 of last seasons exotics and I tried cashing them in. I've had the worst luck in doing so. I never received a single one. I tried a couple at the beginning of the season but never got them and figured I'd just wait until I hit max power and then I'd turn them in. I just hit the max power not long ago, tried cashing in the bounties and the system just wouldn't let me. i had too many umbral engrams. I was saving them for when I wanted to grind out different rolls. I finally got through them and eventually, after I don't know how many errors later, bungie.net finally responded to my request though I could only cash in 3 and I still don't know where the other 2 exotics disappeared off to. I've waited a few days now and I still haven't received the exotics in my post master. I've enjoyed the game quite a bit but I'm kind of getting tired of it. The error codes, hackers online, and too many instances like these that are hard to count keep happening and it's frustrating. I just wanted to make a quick psa not to wait until the following season to cash in exotics. Bungie technically does have a system that allows you to retrieve last seasons rewards but it's apparently broken and doesn't entirely work properly.