Steps to reproduce :

1) Download attached project "mega-neon-pong (full screen fixing).zip" and open in Unity.
2) Build scene 'RetroArcadeGame'(should be already on the list) for Windows Standalone x86_64.
3) Launch game in fullscreen mode in 1680x1050 resolution.
Note: Screen is black, Unity splash screen didn't showed also.
4) Start launcher again and set resolution to 1920x1080 and notice it works as suppose to.

Note: Screen is black also with 640x480 - 1680x1050 resolutions, but if you press Alt+Enter, black screen will be gone.

Note: Works with 1920x1080 resolution.

Reproduced with : 5.4.0b22, 5.4.0b24.

Not reproduced with : 5.2.4f1, 5.3.5p6, 5.4.0b21.