Villagers Despawned

I had villagers in an enclosed space where no mobs could get to them, there were torches in the enclosure with adequate light level. I went AFK for maybe 15 mins and come back to some sort of “watchdog” error, don't remember the exact message, reopened the world and all of my villagers were gone except one. The only villager left had not been assigned a bed or workstation yet during this time. This all happened right after I had placed torches in the enclosures as well if that may provide any further insight.