vilagers despawing

Our villagers are despawning, the usual reason is 'if a villager doesn't have ownership over a bed within "range" of a bell's influence and they are not within an unknown range of a player, they run the risk of being despawned.' Our bell is right in the middle of the beds, and they're STILL DESPAWNING I believe that if nobody is in the overworld, they start despawning.
 My friend told me this and I'm filing a report 
  P.S im on a mulitplayer world (not realms plus)