I second loy1004's problem. I bought 120 or so rare cards to complete the event quest, "find 60 rare cards" and I only recieved one card.
Fixed, you need to reload the page, the number of doubles in the cards after purchase will be up to date
I got the cards, but they didn't count towards the event. I was still able to complete the event with the dungeon though, so I guess it is no problem now. Thanks!