[Qtwebengine] black screen when locale is set

[Tassilo Glander]

Dear List,
I get a black screen where the browser widget is supposed to be when I set the locale to German (de-DE, others also do not work). If I skip this setting, or if I set it to others (examples: en-US, en-GB, zh-CN), the web page renders as expected. 

I build qt locally on Windows 7, Visual Studio2015 SP2, using the Windows 10 SDK and could reproduce the behavior in qt versions 5.5.1, 5.6.0 and dev, so I guess it occurs everywhere. However, I could not reproduce this with the precompiled version of Qt (official download, I used 5.6.1). 

So I suspect it to be an issue of my build and would like to ask for opinions. Could it be about the specific Windows SDK? I configure with 
configure -confirm-license -opensource -nomake examples -nomake tests -debug-and-release -force-debug-info -platform win32-msvc2015

Below you find a minimal example that reproduces the error.
Best,
Tassilo

#include "QMainWindow"
#include "QLabel"
#include "QWebEngineView"
#include "QApplication"
#include <locale>

int main(int argc, char *argv[])
{
    // works
    //std::locale loc("en-GB");  
    //std::locale loc("en-US");  
    //std::locale loc("en-NZ");  
    //std::locale loc("af-ZA");
    //std::locale loc("zh-CN");
    
    // if one of the following locales are set, black screen is shown instead of web page
    std::locale loc("German_germany");  
    //std::locale loc("de-DE");  
    //std::locale loc("nl-NL");  
    //std::locale loc("cs-CZ");
    //std::locale loc("es-ES"); 
    //std::locale loc("vi");
    std::locale::global(loc);

    QApplication app(argc, argv);	
    QMainWindow* mainWindow = new QMainWindow();
    QWebEngineView* webView = new QWebEngineView(mainWindow);
    webView->setUrl(QUrl(QString("http://www.google.de")));
    mainWindow->setCentralWidget(webView);

    mainWindow->show();
    return app.exec();
}