when i was playing with spectator mode, i accidentally switch to adventure mode, and quickly switch back to spectator, and realize that some hostile mob still chasing me in game mode 3.
So i do an experiment with all the mob that are hostile/neutral
How to reproduce:
1. switch to survival mode
2. provoke hostile/neutral mob
3. switch to spectator mode
4. observe
here is a full report from my own experiment: (the capital ones are the one that still remain hostile in spectator)
skeleton: after it come by, i switch to spectator, it stay for a while like normal, and walk away like normal, not fire any more arrows

witch: after poison myself(and itself) i switch to spectactor, and just walk away and drinking couple health potion

silverfish: after it attack me 2 times i switch to spectator, doesn't follow me anymore

endermite: seems like it doesn't attack me when i am in survival?

SLIME: after it attack me, i switch to spectator and it follow me, and when i stay above ground, it keep jumping in circle trying to get me. back to normal when i switch back to creative

MEGMA CUBE: same with slime

wolf: after it becomes angry wolf and attack me, i switch to spectator, and it become normal wolf again

GHAST: after it sees me, and attack me, i switch to spectator, and it keep chasing me and shooting fireball at me, and when i become the point of view of ghast (make sense?) it try to kill itself (but never success)

zombie pigman: turn to normal after switch to spector

blaze: turn to normal after switch to spector

creeper:turn to normal after switch to spector

guardian: turn to normal after switch to spector

spider: turn to normal after switch to spector

cave spider: turn to normal after switch to spector

zombie: turn to normal after switch to spector

enderman: turn to normal after switch to spector

SO the effect ones are: slime, magma cube, and ghast