Панель инструментов навигации Matplotlib встроена в окно pyqt5 - сброс исходного вида

Я пытаюсь использовать интерактивные возможности рисования matplotlib, встроенные в окно pyqt5 с версией mpl: 2.1.1

Я привел минимальный пример с файлом пользовательского интерфейса здесь:

https://ufile.io/8irs7

и код питона:

import matplotlib
matplotlib.use("Qt5Agg")
import sys

from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg as FigureCanvas
from matplotlib.backends.backend_qt5agg import NavigationToolbar2QT as NavigationToolbar
from matplotlib.figure import Figure

import pandas as pd
import numpy as np

from PyQt5 import  QtWidgets, uic  # works for pyqt5
from PyQt5.Qt import  QVBoxLayout


# import numpy as np
qtCreatorFile = "window.ui" # Enter file here.
# qtCreatorFile = "pssga.ui"


Ui_MainWindow, QtBaseClass = uic.loadUiType(qtCreatorFile)

class PlotSeries(QtWidgets.QMainWindow, Ui_MainWindow):

    def __init__(self):
        QtWidgets.QMainWindow.__init__(self)
        Ui_MainWindow.__init__(self)
        self.setupUi(self)

                #create figure
        self.fig=Figure()

        self.axes = self.fig.add_subplot(111)
        self.axes.grid()



        self.canvas=FigureCanvas(self.fig)
        #add plot toolbar from matplotlib
        self.toolbar = NavigationToolbar(self.canvas, self)

        #create new layout
        layout = QVBoxLayout()

        layout.addWidget(self.canvas)
        layout.addWidget(self.toolbar)

        #add layout to qwidget
        self.plotlayout=self.widgetplot.setLayout(layout)

        #draw the canvas ! 
        self.canvas.draw()
        #now let's call widget 
        self.plot_basegraph()


    def plot_basegraph(self):
        #create simple time series 
        for i in range(0,5): 
            ts=pd.Series(np.random.randn(2000), index=pd.date_range('1/1/2015',freq='h', periods=2000),name="series "+str(i))
            if i==0:
                self.stackTSPD=ts.to_frame()
            else:
                self.stackTSPD=self.stackTSPD.join(ts.to_frame(),how='inner')
        print(matplotlib.__version__)

        self.axes.clear()
        self.axes.grid()

        for i in self.stackTSPD.columns.values:
            t=self.stackTSPD.index.to_pydatetime()

            y=self.stackTSPD[i].values
            self.axes.plot(t,y, label=i)


if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    window = PlotSeries()
    window.show()
    sys.exit(app.exec_())

Масштабирование временных рядов, панорамирование работает, как и ожидалось, но когда я пытаюсь нажать «Домой» - сбросить исходный вид, происходит сбой:

Traceback (most recent call last):
  File "/usr/local/lib/python3.5/dist-packages/matplotlib/backends/backend_qt5agg.py", line 155, in __draw_idle_agg
    self.draw()
  File "/usr/local/lib/python3.5/dist-packages/matplotlib/backends/backend_qt5agg.py", line 127, in draw
    super(FigureCanvasQTAggBase, self).draw()
  File "/usr/local/lib/python3.5/dist-packages/matplotlib/backends/backend_agg.py", line 430, in draw
    self.figure.draw(self.renderer)
  File "/usr/local/lib/python3.5/dist-packages/matplotlib/artist.py", line 55, in draw_wrapper
    return draw(artist, renderer, *args, **kwargs)
  File "/usr/local/lib/python3.5/dist-packages/matplotlib/figure.py", line 1299, in draw
    renderer, self, artists, self.suppressComposite)
  File "/usr/local/lib/python3.5/dist-packages/matplotlib/image.py", line 138, in _draw_list_compositing_images
    a.draw(renderer)
  File "/usr/local/lib/python3.5/dist-packages/matplotlib/artist.py", line 55, in draw_wrapper
    return draw(artist, renderer, *args, **kwargs)
  File "/usr/local/lib/python3.5/dist-packages/matplotlib/axes/_base.py", line 2437, in draw
    mimage._draw_list_compositing_images(renderer, self, artists)
  File "/usr/local/lib/python3.5/dist-packages/matplotlib/image.py", line 138, in _draw_list_compositing_images
    a.draw(renderer)
  File "/usr/local/lib/python3.5/dist-packages/matplotlib/artist.py", line 55, in draw_wrapper
    return draw(artist, renderer, *args, **kwargs)
  File "/usr/local/lib/python3.5/dist-packages/matplotlib/axis.py", line 1133, in draw
    ticks_to_draw = self._update_ticks(renderer)
  File "/usr/local/lib/python3.5/dist-packages/matplotlib/axis.py", line 974, in _update_ticks
    tick_tups = list(self.iter_ticks())
  File "/usr/local/lib/python3.5/dist-packages/matplotlib/axis.py", line 917, in iter_ticks
    majorLocs = self.major.locator()
  File "/usr/local/lib/python3.5/dist-packages/matplotlib/dates.py", line 1061, in __call__
    self.refresh()
  File "/usr/local/lib/python3.5/dist-packages/matplotlib/dates.py", line 1081, in refresh
    dmin, dmax = self.viewlim_to_dt()
  File "/usr/local/lib/python3.5/dist-packages/matplotlib/dates.py", line 839, in viewlim_to_dt
    return num2date(vmin, self.tz), num2date(vmax, self.tz)
  File "/usr/local/lib/python3.5/dist-packages/matplotlib/dates.py", line 445, in num2date
    return _from_ordinalf(x, tz)
  File "/usr/local/lib/python3.5/dist-packages/matplotlib/dates.py", line 260, in _from_ordinalf
    dt = datetime.datetime.fromordinal(ix).replace(tzinfo=UTC)
ValueError: ordinal must be >= 1

Такое поведение началось, когда я попытался встроить этот график временных рядов в форму pyqt5. Когда график открывался отдельно в новом окне GTK, он работал без проблем. Я прикрепил пример с работающей домашней кнопкой, которая открывается в окне, отличном от pyqt...

'''
Created on 16. jan. 2018

@author: gregor
'''

import matplotlib as mpl
import matplotlib.pyplot as plt
# matplotlib.use("Qt5Agg")


# from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg as FigureCanvas
# from matplotlib.backends.backend_qt5agg import NavigationToolbar2QT as NavigationToolbar
# from matplotlib.figure import Figure

import pandas as pd
import numpy as np





class PlotSeries():

    def __init__(self):


        self.fig,self.axes = plt.subplots()

        self.axes.grid()



#         self.canvas=FigureCanvas(self.fig)
        #add plot toolbar from matplotlib
#         self.toolbar = NavigationToolbar(self.canvas, self)

        #create new layout
#         layout = QVBoxLayout()
#         
#         layout.addWidget(self.canvas)
#         layout.addWidget(self.toolbar)
#         
#         #add layout to qwidget
#         self.plotlayout=self.widgetplot.setLayout(layout)
#         
#         #draw the canvas ! 
#         self.canvas.draw()
        #now let's call widget 
        self.plot_basegraph()


    def plot_basegraph(self):
        #create simple time series 
        for i in range(0,5): 
            ts=pd.Series(np.random.randn(2000), index=pd.date_range('1/1/2015',freq='h', periods=2000),name="series "+str(i))
            if i==0:
                self.stackTSPD=ts.to_frame()
            else:
                self.stackTSPD=self.stackTSPD.join(ts.to_frame(),how='inner')
        print(mpl.__version__)

        self.axes.clear()
        self.axes.grid()

        for i in self.stackTSPD.columns.values:
            t=self.stackTSPD.index.to_pydatetime()

            y=self.stackTSPD[i].values
            self.axes.plot_date(t,y, label=i)
        plt.show()



if __name__ == "__main__":
 PlotSeries()  

Благодарю вас !