Villagers despawn in my world when re-loading the chunk.
It happened twice now:
1st time, I went to the nether. I used the nether to reach one of my overworld farms which was 1000+ block away from my villagers. Coming back through the nether, I noticed that one of my villagers disappeared.
2nd time I went to one of my mob farms which was 200/300 blocks away. When I returned, one of my villager dissapeared.
In both cases, the villagers were nametagged and had their profession locked.
Both villagers had a workstation and bed.
Villagers that despawn are tagged and have names, but still despawn.