My camera flickers and it's driving me crazy

I have a third person controller prefab with 1 camera. In the editor it works fine when tested, but in the built .exe it’s like there are 2 cameras (one looking forward and one looking up 60 degrees). The screen flickers between these 2 views. And the mouse look doesn’t work. What could be wrong here?

I know it’s a late answer, but i had the same problem and fixed by deleting a secondary mouse look script in the project. It was from another plugin.
It works fine now.

I am certain that there are no duplicate scripts applied because I deleted the old and added a new FPS controller prefab from the unity standard assets. Could you please give me and example of a debug.log so I can add it to the mouse look and character motor scripts?