title: QChart add axis not show and when hovered info not work correct?
body: <p>I am use pyqt5 to draw a simple chart and need to add custom axis, but when i add axis , the chart not show it, and when hovered signal emit, i need to show corresponding point , but it also not showing, it need to click to show.</p>
  
  <pre class="lang-py prettyprint-override"><code>class Demo(QChartView):
      def __init__(self):
          super().__init__()
          self.chart = QChart()
          self.setChart(self.chart)
          self.setRenderHint(QPainter.Antialiasing)
  
          axis_x = QValueAxis()
          axis_x.setTickCount(10)
          axis_x.setTitleText('x')
          self.chart.addAxis(axis_x, Qt.AlignBottom)
  
          axis_y= QValueAxis()
          axis_y.setLinePenColor(Qt.red)
          self.chart.addAxis(axis_y, Qt.AlignLeft)
  
          series = QLineSeries()
          series.setPointsVisible(True)
          series.hovered.connect(self.show_tool_tip)
          series &lt;&lt; QPointF(1, 5) &lt;&lt; QPointF(3.5, 18) &lt;&lt; QPointF(4.8, 7.5) &lt;&lt; QPointF(10, 2.5)
  
          series.attachAxis(axis_x)
          series.attachAxis(axis_y)
          self.chart.addSeries(series)
          self.value_label = QLabel(self)
  
      def show_tool_tip(self, pt, state):
          pos = self.chart.mapToPosition(pt)
          if state:
              self.value_label.move(int(pos.x()), int(pos.y()))
              self.value_label.setText(f'{pt}')
              self.value_label.show()
          else:
              self.value_label.hide()
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/7d8qW.png" alt="image" title="sample"></p>