Fix Check Cube Hopping Bug

[djpetti]

If you try to move the check cube while the animation is running, it kind of hops around and throws an assertion error. Someone should investigate and fix this.

NOTE: After PR 1 gets merged, this might be no longer that issue. Investigation is needed.

[duffym4]

Cube no longer hops, but still throws the assertion error when dragged during the animation.