Sudden shadows in exported movie

I’m exporting a movie in epic settings, avi file, and this happens:

(login YouTube if the link won’t play)

In almost -every- project.
I’m using UE4.14 with GTX970.

I get weird shadows and it’s driving me crazy!
Of course I got the latest drivers on my GTX, I read on a similar issue that I have to restart Unreal (done that many times) and restart the computer (done that also).

How can we fix these sudden shadows coming out of nowhere?

Let me know please, I’m this close to start loosing my hair!
Thank you!

Anybody here?!