There are 2 options, what is this bug:
"Two in one": The game freezes if two cards are in the same slot.
"Infected card": There is a bug if you bought a card in a store, another card may become an empty card, which stops the game.
1 Yes, I am aware of these bugs.
2 Yes, I have names for them.
3. No, I do not know how to fix the second bug.