This is a known issue in SketchUp 2017 when safe frames is enabled (the gray boxes at the sides of the screens). I’m guessing you have VRay 3 instaled which unfortunately enabled this feature without asking for the users concent or even notifying the user about it. If that’s the case you an open the VRay asset editor and turn off safe frames from the output options. You can also disable it using the Advanced Camera Tools if you have SketchUp Pro. Otherwise you can run “Sketchup.active_model.active_view.camera.aspect_ratio = 0” in the Ruby Console.