I assume you set larger fonts on Windows? Can you try LibreELEC.USB-SD.Creator.Win32-dpi-test3.exe ?
Same issue here on linux.
In my case, only the upper left part of the screen is visible in normal size. But as i cannot resize the window, i can't access the rest of the window.
So in my case, the window size is not calculated correctly.
Fortunately I have a non 4k second screen, so that i can use it.