Viewport has a black border?

So I got on UE4 today and there is a strange thing happening. I am in a blank level using an independent camera actor as a display, rather than a character attached camera. So when I run the game in simulation, it gets a black border around the edges that I have no noticed before. Is this normal or how can I fix it? The border does not appear in the camera pin, viewport, or standalone game. Only when simulating in the editor.