i dont know why but when you go in to spectator mode near hostile mob+bats and squids they will disapeer
MC-55636
spectator mode
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Spectators do not keep mobs loaded. Hostile mobs automatically disappear if no player is within 128 blocks, and have a chance of disappearing if the closest player is within 33-127 blocks. If you're the only player then all hostile mobs vanish if you switch to spectator mode. Which is probably a bad idea but it is intentional (bugfix to another complaint).