Realm Minigame - Memory Battle

When me and my friends try to play one of the minigames provided on our realm, 'Memory Battle', it does not work. To my knowledge, it is supposed to randomize the tiles after the start button is pressed. However, on our realm, it gets stuck, as can be seen in the attached screenshot. I asked someone in the Minecraft Technical Support about this and they sent me here, suggesting that it may be a bug as a result of the latest security fixes.

I would greatly appreciate any help that can be given.