Experiencing a total wipeout of all tamed passive mobs (including ones with name tags) as well as total wipeout of multiple villagers in different villages spanning several chunks (including villagers with name tags). Villagers were in secure housing, iron golems and cats are all missing as well in the village areas. 

Other passive (non tamed) mobs seem to be where they were. There's no issue with random spawns of passive and aggressive mobs either. 

Tried entering new chunks, saving game and re-entering but all entities are completely gone. No hitboxes are visible so they have fully disappeared.