PySide2-uic does not call setObjectName() properly

class MainWindow(QMainWindow):
    def __init__(self):
        super(MainWindow, self).__init__()
        self.ui = Ui_NamedMainWindow()
        self.ui.setupUi(self)
        print(self.objectName())  # Prints empty string

class Ui_NamedMainWindow(object):
    def setupUi(self, NamedMainWindow):
        if NamedMainWindow.objectName():  # Here objectName() is ''
            NamedMainWindow.setObjectName(u"NamedMainWindow")  # This line is never executed
        # ...

class Ui_NamedMainWindow(object):
    def setupUi(self, NamedMainWindow):
        NamedMainWindow.setObjectName("NamedMainWindow")
        # ...