Cards Not Showing

Ok I was playing the game when I noticed something odd. Whenever I get a card drop after a wave it just disappears. Idk what's happening but the card doesn't show. Kindly Help. I'm playing on iOS

Like in the post below. You probably activated autotransmute by transmuting more than one card of that type. You can deactivate it by going in the muni and holding the tower button.or the potion or the items button.