the title menu not showing in table view

I created a subclass inheriting from the QTableView class because I want to have a context menu in the table view that appears after right-clicking.

The problem is that how I create the menu and submenu using the code below

void MyTableView::showContextMenu(const QPoint &pos)
{
    QMenu menu;
    menu.setTitle(QString("Insert..."));//the title menu not showing in table view       

    QMenu subMenu;
    subMenu.addAction(QString("row"));    
    
    menu.addMenu(&subMenu);

    menu.exec(mapToGlobal(pos));
}

unfortunately, the title "QMenu menu" is not displayed, I want to achieve an effect in the style of the outgoing menu, e.g

I am including the code in the attachment. 
the problem is in a file called "mytableview.cpp"

Is this a bug in the Qt library? Have I done something wrong?