F4 works for me on windows 10. I'm not sure what the best place would be to start troubleshooting, but I can tell you it's possible.From what I have seen, I'm guessing there is no way to make this actually fill up the whole screen even when using F4? Hate feeling like I'm stuck in the 90s on a 4:3 CRT.
Edit: Nevermind. I'm assuming you mean the black bars toward the sides. There is no way to fix that.