QNetworkAuthenticationManager does not emit authenticationRequired when using NTLM

class NetworkTest : public QObject
{
    Q_OBJECT
public:
    NetworkTest() : QObject(NULL)
    {
        m_pManager = new QNetworkAccessManager(this);
        connect(m_pManager, SIGNAL(sslErrors(QNetworkReply*, const QList<QSslError>&)), this, SLOT(onSslErrors(QNetworkReply*, const QList<QSslError>&)));
        connect(m_pManager, SIGNAL(authenticationRequired(QNetworkReply*, QAuthenticator*)), this, SLOT(authenticationRequired(QNetworkReply*, QAuthenticator*)));

        QTimer::singleShot(100, this, SLOT(testRequest()));
    }

public slots:
    void testRequest()
    {
        qDebug("!!! testRequest\n");
        m_pManager->get(QNetworkRequest(QUrl("https://something.com/ews/Exchange.asmx")));
    }

    void authenticationRequired(QNetworkReply * reply, QAuthenticator * authenticator)
    {
        qDebug("!!! authenticationRequired\n");
    }
    void onSslErrors(QNetworkReply * reply, const QList<QSslError> & errors)
    {
        qDebug("!!! onSslErrors\n");
        reply->ignoreSslErrors();
    }

private:
    QNetworkAccessManager *m_pManager;
};

} else if (priv->phase == QAuthenticatorPrivate::Start) {
    // If the url's authenticator has a 'user' set we will end up here (phase is only set to 'Done' by
    // parseHttpResponse above if 'user' is empty). So if credentials were supplied with the request,
    // such as in the case of an XMLHttpRequest, this is our only opportunity to cache them.
    emit reply->cacheCredentials(reply->request(), auth);
}

QNetworkAuthenticationCredential cred = authenticationManager->fetchCachedCredentials(url, authenticator);
if (!cred.isNull()) {
...
            return;
 }