placed entities (such as paintings) are disappearing

In my worlds, placed entities such as paintings, armor stands, and item frames keep on disappearing. Nothings dropped, the entities just disappear. Even tamed dogs and villagers disappear too. It is not a matter of mobs killing the dogs or villagers either. I thought it was just an isolated situation on one of the realms I was playing on, but then it started happening on my 1600 day world.