Ancient coins not working

Ok so I'm trying to buy ancient coins to purchase items in the emporium, but when I click "purchase ancient coins" it says "store inventory unavailable. please try again later." So, after that didn't work, I went to the Xbox app, (I am using the pc Xbox version, not steam) and tried purchasing coins there, but when I logged back into the game the coins weren't in my inventory. If this is a common problem, please let me know so I can refund the money I spent.