Sand/Concrete Powder/Gravel are breaking when a piston pulls sand with other sand on top.

When a piston pulls a sand with another sand on top of it, the top sand breaks and any other sand breaks randomly.

 

Expected to: The sand on top of the pulled sand falls, and everyone else too.

 

What happens: The sand on top of the pulled sand breaks. (This also occurs when breaking the bottom sand in the pile)