When in creative mode and attacking zombie or zombie pigman in the overworld with either gamerule doMobSpawning set to true or false will cause the spawned zombie to attack you.

The spawned zombie will continue to pursue you even after there is at least 50 blocks between you and the zombie.
Zombie pigmen when attacked in creative mode will also have the same behavior.

When reloading the map, the zombies show no aggression towards you, even after hitting them, as you would expect in creative mode.