QWizard initializePage is not called

Question

As It's described in the docs initializePage should be called when the Wizard is started.

However in my code initializePage is not being called.

I notice that validatePage() is also not called, so I must be making a mistake.

Someone spots the error?

import sys
from PyQt5 import QtWidgets, uic
from PyQt5.QtWidgets import QWizard, QWizardPage, QWidget

app = QtWidgets.QApplication([])

class MainWizard(QWizard):
    def __init__(self, parent=None):
        super().__init__(parent)
        uic.loadUi('inittest.ui', self)
        self.addPage(Page1(self))
        self.addPage(Page2(self))
        self.show()

class Page1(QWizardPage):
    def __init__(self, parent=None):
        super().__init__(parent)
        # instantiate the widgets
        self.label = parent.findChild(QtWidgets.QLabel, 'label')
        # self.initializePage()

    def initializePage(self) -> None:
        self.label.setText('Page1 initialized')

class Page2(QWizardPage):
    def __init__(self, parent=None):
        super().__init__(parent)
        # instantiate the widgets
        self.label_2 = parent.findChild(QtWidgets.QLabel, 'label_2')
        # self.initializePage()

    def initializePage(self) -> None:
        self.label_2.setText('Page2 initialized')

if __name__ == '__main__':
    main = MainWizard()
    main.show()
    sys.exit(app.exec_())

my ui file, inittest.ui

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>Wizard</class>
 <widget class="QWizard" name="Wizard">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>400</width>
    <height>300</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>Wizard</string>
  </property>
  <widget class="QWizardPage" name="Page1">
   <widget class="QLabel" name="label">
    <property name="geometry">
     <rect>
      <x>170</x>
      <y>80</y>
      <width>47</width>
      <height>14</height>
     </rect>
    </property>
    <property name="text">
     <string>TextLabel</string>
    </property>
   </widget>
  </widget>
  <widget class="QWizardPage" name="Page2">
   <widget class="QLabel" name="label_2">
    <property name="geometry">
     <rect>
      <x>80</x>
      <y>80</y>
      <width>47</width>
      <height>14</height>
     </rect>
    </property>
    <property name="text">
     <string>TextLabel</string>
    </property>
   </widget>
  </widget>
 </widget>
 <resources/>
 <connections/>
</ui>

I expect the text of the label to be set. It doesn't