This test failed for nightly build ReleaseTag=6.1.0-preview.671:

[-] -WindowStyle Normal should work on Windows
[00:17:01] Expected exactly {Normal}, but got {Hidden}.

While the logged details are inconclusive, the most likely cause is the call to GetWindowPlacement in user32.dll returned FALSE.

The test should be updated to detect the return value and throw a Win32Exception with the return value of Marshal.GetLastWin32Error.

if (!GetWindowPlacement(...))
{
   int win32Error = Marshal.GetLastWin32Error();
   throw new Win32Exception(win32Error, string.Format(CultureInfo.InvariantCulture, "GetWindowPlacement failed with 0x{0:X}", win32Error));
}