experimental world is still having issues. Villagers despawn and change professions too often seemingly because they cannot find their way to their workstation.. sometimes they just randomly disappear. (Name tag mobs disappear too.) survival mode increases the likelihood that villagers will despawn.  If i copy my experimental world, the copy world doesn’t offer the experimental mode button. All my progress has been made on an experimental world since the 1.9.0.15 update. A month after that update you suggested everyone copy their world and switch to experimental because the villager mechanics in normal game mode had crashed. And trading was not available. Plus other problems.. anyway experimental world/ mode village mechanics still need work.