All mobs in a area disappear, also tamed and named mobs

somtimes random mobs disappear.

from what i see it happends when chucks get loaded when you join or enter through a nether portal.

Last time every mob in the area disappeared, including, 15 villagers, coloured sheep on a lead, tamed dog and a named axelotl.

the bug has happend more then 3 times in 1 month and is very annoying to deal with.

Hopefully there is a way to fix it