GameObject disappear as I move/rotate the camera

Hello everyone,

I am facing a problem and might have a very simple solution, but still didnt figure it out. I have imported a fantasy environment from the asset store, added FPS character controller and while wondering in the environment, I see objects appear and disappear as I rotate the camera (pressing A,D) keys, and this happens all the time.

some posts mentioned that I have to remove the animation component from static object, but I have none..

Check the attached picture. (Note that the character remains the same place, only rotating from left to right, results in these 3 pictures).

Just to mention that trees have LOD properties, but non trees are disappearing as well.

Thank You,