I'm sorry but, as you can see in my screenshot, the problem doesn't happen normally so, you must either have some problem with your video settings, or have applied a tweak in the simulator that is causing this. Or, possibly, another addon you installed has applied a tweak that is causing this.
With "clean installation", you mean you ALSO removed ALL these folders ?
%APPDATA%\Lockheed Martin\Prepar3D v4
%PROGRAMDATA%\Lockheed Martin\Prepar3D v4
%LOCALAPPDATA%\Lockheed Martin\Prepar3D v4
This is the only "clean" installation but, of course, will require that all the addons that doesn't use the add-on.xml in the Documents\Prepar3d v4 Add-ons folder (like we do), to be reinstalled, because it will remove your old Prepar3d.cfg, the scenery.cfg, the DLL/XML files and the list of active addons.