Unable to purchase co-op commanders

Hello. I’m capped at level 5 and trying to purchase Karax from within SC2, and all I see is an empty blue box after clicking the orange “purchase” button. Furthermore, I can’t find where to purchase Karax from the Blizzard store site: https://us.shop.battle.net/en-us/family/starcraft-ii#commanders

that means that you are unable to communicate with the shop server. perform a test of your connection and post the result here.

My connection is otherwise fine; I’m able to play co-op games, etc. Regardless of why I can’t reach the shop server, it’s odd that Karax isn’t listed on the Battle.net website.