- As specifically as I can explain this, if you are crouching/riding on a rolling ball and the ball comes in contact with two different levels of ground below that are extremely close together, you are unable to ride the ball at that point while trying to crouch.
I suspect it may be because the ball instantaneously shifts upward a number of pixels whenever it goes onto slightly higher ground from below, but I'm not really sure.
The bug can be a minor issue if it comes in contact with a moving platform, but you must not get off the rolling ball (nor leave it behind). This is usually the case when the moving platform goes through the ground.