Passive mobs despawned

Sooo, I was in the nether and I went through the portal to go to the overworld and just as I appeared I noticed that my vilagers despawned, I thought they just were't showing to me. Tried to interact with them. but nothing happened. Then I went to my chicked farm and check them and they were't there as well, like most of my passive mobs.

Maybe anyone experienced this? Or has an idea what to do?

THANKS!