Destruction of QAxObject does nor properly release COM Object

// main.cpp

#include <QAxObject>
#include <QCoreApplication>
#include <QDebug>
#include <QTimer>

#include <combaseapi.h>

int main(int argc, char *argv[])
{
    qInfo("main: Starting test...");

    QCoreApplication a(argc, argv);

    if (SUCCEEDED(CoInitializeEx(NULL, COINIT_MULTITHREADED))) {

        qInfo("main: CoInitializeEx() succeeded");

        QAxObject *axObject = new QAxObject();

        axObject->setControl("MyComObject.ComObject");

        axObject->dynamicCall("SayHello");

        delete axObject;

        // Message 'ComObject: Object destroyed' is expected to appear around here

        qInfo("main: QAxObject deleted");

        CoUninitialize();

    } else {
        qFatal("main: CoInitializeEx() failed");
    }

    // Properly shut down the calling application
    QTimer::singleShot(5000, &a, SLOT(quit()));

    bool ret = a.exec();

    qInfo("main: Done...");

    return ret;
}

// Simple COM object in C#

using System;
using System.Runtime.InteropServices;

namespace MyComObject
{
    [Guid("8157be30-e99a-4b14-b88d-bc8db831047b")]
    public interface IComObject
    {
        [DispId(1)]
        void SayHello();
    }    

    [Guid("6c080298-7b10-494b-84af-38b6db12a7d4"),
    InterfaceType(ComInterfaceType.InterfaceIsIDispatch)]
    public interface ComObjectEvents
    {
    }    

    [Guid("63d3c24d-2a60-4338-b312-63a771c580bd"),
    ClassInterface(ClassInterfaceType.None),
    ComSourceInterfaces(typeof(ComObjectEvents))]
    public class ComObject : IComObject
    {
        public ComObject()
        {
            Console.WriteLine("ComObject: Object created");
        }        

        ~ComObject()
        {
            Console.WriteLine("ComObject: Object destroyed");
        }        

        public void SayHello()
        {
            Console.WriteLine("ComObject: Hello!");
        }
    }
}

// Output of main.cpp

main: Starting test...
main: CoInitializeEx() succeeded
ComObject: Object created
ComObject: Hello!
main: QAxObject deleted
main: Done...
ComObject: Object destroyed