Thanks to everyone who reported the problem with furniture occasionally disappearing when pushed by a piston. The worlds you sent me allowed me to figure out the problem quickly.
It’s already fixed and to be released soon to Google Play as 2.1.11.
One thing to watch for is the existing worlds that had this problem may still keep exhibiting it until all affected furniture is replaced.
What was happening: furniture design garbage collector was not looking at moving blocks, and it was possible for it to mark a furniture design as unused when it was only present as a moving block. Then, when the piston stopped, moving block turned into terrain block and chaos ensued as the design was gone. This wasn’t happening very often as collector does not run too frequently, plus your furniture must have been only present as moving blocks (not in inventory or in terrain).
