Villagers despawn even when safe.

On Realms for some strange reason I have had to rebuild my village three times now as my villagers keep despawning.

I have attached their living accommodation for reference of how the houses are.

I have checked for gaps in the fencing I have used and the place is fully lit so I know no mobs can get in there.

Is anyone else having this problem? I have searched but I could only find one open ticket on all passive mobs disappearing but mine only seems to be targeted at the villagers.