I have an area where I have ten villagers fenced off with their job blocks, but when I try to keep one in a specific space, he disappears when I go to sleep or move far enough. This happened three times:

1. Brought a new cured zombie villager and stuck him in the fenced off space with a brewing stand. I left and came back to find him gone.
2.  Brought a new cured zombie villager, nametagged him, and put him in a fenced off space right next to the buggy one.  I then moved a nametagged cartographer I'd had for a long time to the buggy space with his cartography table. Went to sleep a little ways away, came back to immediately find him gone. The one next to the buggy space is still there.
3. Gave myself a villager spawn egg and spawned a villager in the buggy spot. Went downstairs and did things about 21 blocks down and 15 blocks south, came back to find him gone.