Sticky Pistons (powered by an Observer) pushing blocks under the Observer that is powering that Sticky Piston, causes the Sticky Piston's block to be stolen by the Observer.
This video focused mostly on Melons being deleted, but as Rory Gatens reminded me, melons break when smushed.
Only focus on the part of the video showing the Sticky Piston's block being stolen. (Basically the first 30 seconds of the video)
This may affect other consoles.