Issues loading QWidgets containing QQuickWidget into QStackedWidget in Qt5.15

mchabala

Hello,
I'm developing a Qt application and would like to incorporate QML through QQuickWidgets, but am running into some issues. To give some context, I created a simple project with the goal of adding two QWidgets containing QQuickWidgets to a QStackedWidget and navigating between them. Something like this:

MainWindow::MainWindow(QWidget *parent)
: QWidget(parent)
{
   // Create Next PushButton and connect to function that updates current page when clicked
   pb1 = new QPushButton(this);
   pb1->setText("Next");
   connect( pb1, SIGNAL( clicked() ), this, SLOT( showNextWidgetInStack() ) );

   // Create Previous PushButton and connect to function that updates current page when clicked
   pb2 = new QPushButton(this);
   pb2->setText("Previous");
   connect( pb2, SIGNAL( clicked() ), this, SLOT( showPreviousWidgetInStack() ) );

   // Create QStackedWidget and add two "pages"
   sw = new QStackedWidget();
   QQuickPage *page1 = new QQuickPage( "test_page1", this );
   QQuickPage *page2 = new QQuickPage( "test_page2", this );
   
   // Add "pages" to stacked widget
   sw->addWidget(page1);
   sw->addWidget(page2);
   sw->setCurrentIndex(0);
   
   // Add everything to latout and set it
   QVBoxLayout * mainLayout = new QVBoxLayout;
   mainLayout->addWidget ( pb2 );
   mainLayout->addWidget ( pb1 );
   mainLayout->addWidget ( sw );
   setLayout(mainLayout);
}

where showNextWidgetInStack and showPreviousWidgetInStack increases/decreases the index of the QStackedWidget to display the next element and QQuickPage is a widget containing a QLabel and a QQuickWidget:

QQuickPage::QQuickPage( QString product, QWidget *parent )
    : QWidget(parent),
      _product(product)
{
   QLabel *productLabel = new QLabel;
   testLabel->setText(product);

   QString qmlFile = qmlRootDir + "/" + product + ".qml";

   // Load .qml page contents into QQuickWidget
   qqw = new QQuickWidget;
   qqw->setSource(QUrl::fromLocalFile(QFileInfo(fileName).canonicalFilePath()));
   if ( qqw->status() == QQuickWidget::Error )
   {
       // Error handling here... 
   }

   // Set the background color to specific theme and set resize mode for scaling
   qqw->setClearColor(QColor(qmlBackgroundColor));
   qqw->setResizeMode(QQuickWidget::SizeRootObjectToView);

   // Display QLabel and QQuickWidget built from QML
   QVBoxLayout * mainLayout = new QVBoxLayout;
   mainLayout->addWidget(testLabel);
   mainLayout->addWidget(qqw);
   setLayout(mainLayout);
}

Attempting to do this causes the application to crash, specifically at Qt5Core.dll!ZNK7QObject8propertyEPKc in the call stack.

What's strange is that:

If add one QQuickPage it works as intended if the QML page that is loaded is using QtQuick.Controls 1, but fails if using QtQuick.Controls 2
If adding QQuickWidgets to the QStackedWidget directly they appear without issue, regardless of if QtQuick.Controls 1 or QtQuick.Controls 2 is used.
I had this working on Qt 5.12.12, but after building locally from source using the following command: ..\qt-everywhere-src-5.15.9\configure -v -prefix D:\buildQt\qt-5.15-install -commercial -release -platform win32-g++ -shared -nomake tests -nomake examples -confirm-license -no-feature-gssapi -no-harfbuzz -no-opengl -no-dbus -qt-libpng -qt-zlib -qt-libjpeg -skip qtx11extras -skip qtwayland -skip qtvirtualkeyboard -skip qttranslations -skip qtspeech -skip qtserialport -skip qtserialbus -skip qtsensors -skip qtscxml -skip qtscript -skip qtremoteobjects -skip qtpurchasing -skip qtnetworkauth -skip qtmultimedia -skip qtmacextras -skip qtlocation -skip qtgamepad -skip qtdoc -skip qtdatavis3d -skip qtconnectivity -skip qtcharts -skip qtcanvas3d -skip qtandroidextras -skip qtactiveqt -skip qt3d -skip qtwebview -skip qtwebsockets -skip qtwebglplugin -skip qtwebengine -skip qtwebchannel things no longer work.

Any advice/input/help on this would be greatly appreciated!

Thanks in advance