Disappearing Chickens

So, recently started a new Minecraft world, and I've been encountering a disappearing chickens bug. I'm not sure if it happens with other mobs, I've only farmed chickens so far. What'll happen is, I leave to go mine or farm or whatever, usually a decent distance away from the farm, and I come back, and there's plenty of eggs, but not plenty of chickens like there should be. A log out/in fixes it, but during the time where the bug is present, the chickens aren't there. I can't damage them, and they don't show up as present entities in the debug screen, but it says the total entity count right. First attached image shows the bug in action, second shows how it should look after a re-log.