UE-24478 isn’t fixed in 4.11 preview 3 too.
Hello , as an Turkish keyboard user, I just had the same issue as compiling vxgi integrated engine source, fixed it by your suggestion, thanks. I tried to compile 4.11 preview, still have the same issue by the way.
(Teşekkürler 
)
Sorry to necro but;
For those who experiencing error with undefined “CultureInfo”:
Change …ToUpper(new CultureInfo(“en-US”, false));
to
…ToUpper(new System.Globalization.CultureInfo(“en-US”, false));
At the end,line should look like this:
string PCHGuardDefine = Path.GetFileNameWithoutExtension(PrecompiledHeaderIncludeFilename.AbsolutePath).ToUpper(new System.Globalization.CultureInfo(“en-US”, false));