Occasionally instead of seeing an opponent's cards as normal, one of them will display as an all white rectangle. I'm not sure if it's related to a specific card but if it is maybe you can figure out which one it is. The one that hit me had:

Attack - 5
Defense - 3
Damage - 4

It definitely wasn't an ether type card since I would have blocked the damage and it didn't seem to heal or do any extra damage.

This is not a problem to a specific card. The solution is to re-download the application.
This problem will be resolved in the next release.

Good game.