Mine did this too. I was able to scroll up and the grey border scrolled with it and revealed the claim button.
Or just go to your STASH - REWARDS screen and claim them from there.
Or just go to your STASH - REWARDS screen and claim them from there. That’s the store. Your stash is located in your inventory.
Ah, see it now. Submit a ticket to support if your stash is empty and you didn’t receive any rewards.