Memory Game - Shuffle Group and Mask On cannot happen at the same time

I am fixing my matching game that is based on your Memory Game in the User Guide.
If both the Shuffle Group and Mask On Action happened at the same time (which is usually set at Execute on Page Load). They messed up. The Mask On is missing or the shuffle is strange. I think this maybe a bug. The work around for me is to Delay the Mask On for 100ms to avoid the two actions collide.