Many mobs don't walk when player is in spectator mode

I have seen noticed mobs like cows, sheep, horses, creepers, zombies, skeletons, and spiders do not walk when the player is in spectator mode. The only time they move is if they are forced to, for example if a creeper is next to a cat it will move, or if a zombie is on fire it will move. Endermen will not walk when player is in spectator, but they will teleport. When I switch to creative or survival mode these mobs start walking again.