Landscape flickering from black to normal

Hi. I’m having a huge problem in the Editor related to the landscape. Basically, the Landscape looks normal until I start to either move the camera or just highlighting things on the editor. Then, the entire terrain become to flicker to black, sometimes taking time to go back to normal.

It’s really annoying. I was guessing that this could be releated to the Post Process, since I’m trying to make a Cel Shading PP on this project.