A lot of people are reporting ZOMBIE villagers despawning, this is NOT that.

First time this happened I had 4-5 villagers, all librarians in a little fenced in area outside my house and a Zombie villager named Howard (I know I said this wasn't about zombie villagers but this is important for later.  One day i traveled to the nether for some wither hunting.  while there I died and respawned in my house.  I quickly returned for my items and promptly left to avoid further loss. When i got back to my base I went to check on my villagers but ALL of them were gone except for Howard, my zombie villager.  Since the nearest village is a ways away i decided it'd be easier to cure Howard and use him for trading so I built some Villager Apartments nearby, cured Howard and gave him a room.  After a while I went and got another villager and gave him a name (Marcus) and assigned him the room next to Howard.  Then this morning I loaded up Minecraft and set myself up next to my mob farm and went afk for a couple hours.  When I returned I killed the mobs and went to go trade with my villagers but Howard had disappeared.  But Marcus is still there.  i checked to see if he got out some how but no dice.  i would like to note that i doubt he or my other despawned villagers turned into zombie villagers and despawned in the known bug way because they were all in well lit and enclosed spaces and their surroundings are well lit too.