I logged out of my world around an hour ago. Reloaded it to find all my villagers have completely disappeared in my iron farm, as well as the cows in my cow cooker. 

Loading up a copy of the world in creative to check stuff (invisibility etc), golems are still spawning but when doing /execute @e[type=villager] i get no targets match selector.

They were all in the same chunk, no border crossing at all just disappeared but village still exists.