My villagers are despawning

Basically I will cure zombie villagers and then log out for the day come back the next day they are gone no trace of them and a zombie do not kill them because I logged off beside them it's really annoying I literally lost my mending library in

I am on bedrock and it's the latest update this is been going on for two days and it's really annoying I keep losing my best villagers I'm afraid to go onto my other world because I have really good villagers there please please fix