"Obtainable items" unavailable from menu

Regarding items you can claim from the obtainable items menu at the top of the screen, next to the daily mail and the currency overview, items such as founder’s pack treasure chests and Twitch-watching rewards, I have around 9 items but none of them appear. It just keeps telling me there’s been an error, and other times the error doesn’t appear, but it just says I have no items to claim.

I tried going back to the character select screen and re-entering the game, but that didn’t help.