Mobs despawn

Hello,

All mobs of my village despawn (animals, villagers, spiders, zombies ). Last night, I saved the game before quitting, and today when I started, all of the mobs despawn. 

This is the second time it has happened at the same version 1.17.40, in different saves and mobile phones.

In both cases, I was playing in the local network.

Cell Phones: iPhone 11 and iPhone XR, both running iOS v15.0.2

Minecraft v1.17.40