Starting a normal Minecraft survival world, I found a village located mostly in a Plains biome that branched over slightly to a woodland hills biome. As far as interaction with the villagers the most I did was trade with one of them, and sleep in one of the beds in the village. After a few days, i returned from mining from far away, and discovered that every villager was gone, apart from the iron golem. I hopped into spectator mode and couldn't find them anywhere. 

• I slept every night in game so zombies could not have killed them.
• The chunks in which the village was located were loaded the entire time. 
• I was able to find a wandering trader, a ways from the village.

Hope this gets solved soon!