Stars do not appear in the sky, even when everything is pitch black. Also, turning off clouds disables global lightning.
Are you using compatibility mode? I guess that’s the reason probably, because some game elements are taken off to increase performance on this mode.
I tested with all three compatibility modes (though one of them instantly crashed my game as soon as it launched), out of the other two, one didn’t even have a sky and the other one was fine but was missing the stars, as you can see in the screenshot.
Thanks for reporting!