[Mne_analysis] CSD might break montage

[Gabriel Weindel]

        External Email - Use Caution        

I was on the dev branch after the commit #7863 on CSD on github, but 
even when updating to the master branch with the link you provided I 
still have the same error.

I tried with the example in 
https://mne.tools/dev/auto_examples/preprocessing/plot_eeg_csd.html#sphx-glr-auto-examples-preprocessing-plot-eeg-csd-py
Topomap works (as for my data actually) but when I use 
mne.viz.plot_compare_evokeds([evoked_csd], picks='csd', axes='topo')
I have the same error. So it seems to be specific to plot_compare_evokeds

I posted a gist in case it's spares you or others some time 
https://gist.github.com/GWeindel/2af99b1a3b07d2d75d8e27cbacdf741e

Best,
Gabriel