My villagers I have trapped in a large house are disappearing. Two of them were even named.

I suspect it has something to do with my game client crashing/disappearing when I alt-tab to other windows sometimes. Full story:

I healed 3 different villagers and transported them to a large house with a ceiling 3 high and a single entrance with redundant openings. Meaning I had a fence gate inside and then I would block up the outer entrance, I named the first two because I had read that would stop them from despawning when they were still zombie villagers.

I successfully bred several of them and now I had 5-6 villagers each with their own bed and everything. Its been like this for several different play sessions. Was still getting the town ready to release them. Tonight I load the game up and go in the house and find all but two villagers are gone. The remaining two were normal villagers, not my named ones with professions. They soon made a baby.

I was upset obviously. I alt tabbed out to search for how this was and what I could to do fix it or avoid it. In the meantime my client disappeared. To be clear, I alt tabbed while IN the house with the two villagers and the baby.

I restart the client and load into the world and into the house where there is now ONLY the baby. All my grown villagers are gone. They didn't become zombies, they didn't glitch between blocks.