[Mne_analysis] The arrowmap does not display arrows

[M]

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Hi,
I am using MNE 0.20.6-Python 3.7.6 on a Windows OS. The example code
plot_evoked_arrowmap.py on
https://mne.tools/stable/auto_examples/visualization/plot_evoked_arrowmap.html#sphx-glr-auto-examples-visualization-plot-evoked-arrowmap-py
does not display arrows, as shown in the attachment. There is
a UserWarning: Tight layout not applied. The left and right margins cannot
be made large enough to accommodate all axes decorations. This warning
comes from the plot_arrowmap()
<https://mne.tools/stable/auto_examples/visualization/plot_evoked_arrowmap.html#sphx-glr-auto-examples-visualization-plot-evoked-arrowmap-py>
Is this a bug of plot_arrowmap() ? Can you help me with this? I want to
generate arrowmaps based on MEG data.
Thanks.
Kind regards,
Min
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