I just looked around for around the 100th time and came across this that re-linked my twitch prime to bungie (though it doesn't seem like I'm getting any of the previously claimed rewards that I didn't receive) I hope this helps you and do reply to me if this works for you (there is new loot available currently on the 2nd of December 2020 maybe you will receive it if you link it now and then claim it) I already claimed the current reward before the re-link so I can't say if it works for sure but I did get a notification via my account that I granted twitch access again.