Didakhos

Hi, I hope this helps. I had this very same issue. I linked my Twitch prime and Social club accounts like 5 days ago, and eventually got the ammo and money rewards but for a couple of days there was no signs of the carcano rifle/outfit/emote just as you experienced. Finally, today I checked again and I had all those unlocked for free, so I recommend you to recheck if the problem was solved for you too.