Man made things in my world are being deleted

So, Me and my friends HATE this issue, everything player made is being deleted. (So: World full of things >  How it first spawned ) It so we cannot play Minecraft anymore because our worlds are always being deleted...

Please fix this Bug Mojang!

 

So, we are trying to do another series and see if the bug still exists or if it stopped

Results: I left the game an the rejoined and it was Reset wow....