Zombies dont forget!

I was trying to create a sort of smoke grenade, based on particle, teleporting and summon commands; pratically, when the player drops a firework charge, an invisible squid is spawned and teleported to the dropped item, then the item is killed, lots of particle commands are toggled, the squid is killed, the player recive an invisibility effect and is teleported at the same position he was. The teleporting command should make the mobs forget your position, and this works for all the mobs except zombies. An also the teleport command (in this case is /tp @e[type=Squid] @e[type=Item,id=402]) is a bit buggy: sometimes works, sometimes not.
I attached the screenshot of the system .