For a while now, my tamed and friendly mobs have been randomly disappearing. This has mostly affected pigs and sheep, and may affect villagers. But recently I had an iron golem and a nametagged donkey equipped with a saddle and chest and with items in the chest vanish. Neither the golem nor the donkey could have suffocated in walls because they were in large open fields and attached by lead to a single fence post. Searching for these vanished mobs finds nothing. In the case of the donkey and golem they left the lead and the fence post behind. I'm afraid to continue work on my village if all of the villagers and mobs I worked so hard to find and being there are just going to disappear! Is this some sort of bug?