Problem receiving signals between QNetworkReply, QTimer::singleShot and qeventloop

[Desujoi]

I'm having rather peculiar problem with my Qt application. The application communicates with another application through REST API. Calls are made by functions that will either return the response or empty value if timeout happens.
Code

QEventLoop loop;
    QNetworkReply* reply = nam_.post(request, jsonBytes);
    connect(reply, SIGNAL(finished()), &loop, SLOT(quit()));
    QTimer::singleShot(TIMEOUT, &loop, SLOT(quit())); //timeout
    QTimer::singleShot(TIMEOUT, this, SLOT(sayHello())); //timeout
 
    DBG << "pv Loop begin";
    loop.exec();
    DBG << "pv Loop end";
    QByteArray response = reply->readAll();
    return bytesToVariantMap(response);

QEventLoop loop;
    QNetworkReply* reply = nam_.post(request, jsonBytes);
    connect(reply, SIGNAL(finished()), &loop, SLOT(quit()));
    QTimer::singleShot(TIMEOUT, &loop, SLOT(quit())); //timeout
    QTimer::singleShot(TIMEOUT, this, SLOT(sayHello())); //timeout

    DBG << "pv Loop begin";
    loop.exec();
    DBG << "pv Loop end";
    QByteArray response = reply->readAll();
    return bytesToVariantMap(response);

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In single try this works. However when multiple threads are running and calls are made in rapid succession problems occur: loop.exec() never exits and sayHello() is never executed. It seems as if the whole event system becomes unpredictable. Oddly enough adding delay before loop.exec seems to reduce the problem.

QThread::msleep(300); //Without this delay, loop.exec might deadlock (WTF...)
loop.exec();

QThread::msleep(300); //Without this delay, loop.exec might deadlock (WTF...)
loop.exec();

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I tried this in both Qt 5.4 and 5.5