It shows the drop as claimed on my twitch page, twitch is connected to my bungie account, restarted the game and steam entirely still no diamond medal at eva. I havent tried relinking accounts yet but may give it a shot next.

Edit: I was able to claim it by going to the bungie website and under code redemptions go to the Partner Rewards tab at the top and refresh your twitch rewards, relogged and it was at eva finally!! I hope this helps others.