I recently set up an iron farm, and used villagers from my breeder to populate it.

I went away to work on some other projects and came back to none of my 6 villagers and no idea where they could have gone.

This started about the time when 1.15.0 came out...

I have had to cheat them back in over 5 times and I don't like to cheat...

I have been going into creative to spawn them back in but I'd like to keep them spawned in the way they are...

I've traded with them, built a glass case around them, and watched them for a while to see if any mob could get to them. Nothing is working.