Random entities disappearing every time I exit Minecraft app

Every time I exit the Minecraft app, either a mob I've tamed and named, armor stands, or paintings disappear. They aren't entities I've recently tamed or placed, I've had them in my world for months, but lately they keep disappearing one by one. Sometimes only one disappears, or sometimes 10 entities will disappear at the same time. I also make sure to save the game before exiting the app and swiping it out, but it happens anyways.