The same thing is happening to me in the U.S. Region. I am trying to buy 4 mythic wild cards. I was able to add the funds to my Steam wallet but then after I am now locked out of buying anything from the store through Steam. I checked and I can still make purchases through the mobile app but I have 20 dollars in my Steam wallet now that I would like to use and not have to re-spend 20 dollars on the mobile app.
The same thing is happening to me in the U.S. Region. I am trying to buy 4 mythic wild cards. I was able to add the funds to my Steam wallet but then after I am now locked out of buying anything from the store through Steam. I checked and I can still make purchases through the mobile app but I have 20 dollars in my Steam wallet now that I would like to use and not have to re-spend 20 dollars on the mobile app.