I loaded into my minecraft world to find that a part of my creation was randomly missing. I never did anything to it and by the looks it seemed it just disappeared. There is a little grass hill where some of the building used to be, and this was previous chunks that I destroyed earlier. There seems to be a shadow still there, but im not sure what that is from. The old blocks(grass, grass block hill) seemed to replace the new ones and destroy my creation, and it is very frustrating and a bug that is a problem to me.