APK behaving different to editor

so i just tried to release my game and relized that the apk is not working as the unity editor.

i have a game with 300 ai's, a small city and the code is super simple. in the editor, the zombies run from one to another and infect the others. but when i try the APK on the mobile, they are not moving when im not looking at them?? like, i have a camera in my game and i can move it around the city, but only the zombies i am looking at are moving/ using the update function, everybody else is like "frozen" until i look at them. this is not happening in the editor, just in the apk build...

any ideas?