Battlenet won't let me buy DLC?

Hello all, basically what the title says. I already have D2R, even verified its on my account. But when I try to buy the new DLC it says I need the base game to purchase and tries to get me to buy the infernal edition. What's going on here? There's no way to bypass this either it keeps redirecting me or forcing me to cancel the purchase. I just want to buy the DLC I dont need to buy the base game again for $40