mt19937 returns same number even though it is seeded

I have simple random generator code that returns different numbers using cl and g++ compilers in Windows. Strangely, the same code in Qt doesn't return different numbers. The code is

#include <random>
#include <iostream>

class RandGen
{
public:
    RandGen() :  m_generator(m_seeder())
    {
    }

    std::random_device m_seeder;
    std::mt19937 m_generator;

    int getNum()
    {
        std::uniform_int_distribution<> dist(0,5);
        return dist(m_generator);
    }
};


int main()
{
    RandGen rg;

    for(int i(0); i < 5; ++i){
        std::cout << rg.getNum() << " ";
    }
    std::cout << std::endl;

    return 0;
}

In Visual Studio, the result is

With g++ via cygwin, the result is

Now running same code with Qt using Desktop Qt 5.9.1 MinGW 32bit, it returns same values.

The .pro file is

QT += core
QT -= gui
CONFIG += c++11
TARGET = Ports
CONFIG += console
CONFIG -= app_bundle
TEMPLATE = app