Problem with titles and subplot

Minor note: the images that were uploaded already got caught up in the code formatting. I've fixed that so that the uploads display, at least.

To clarify, the titles that are missing from the multi-panel plot are the ones with the days of the week? (Because it looks like the overall title — "Temps d'utilisation en cumule par jour" — is present in the multi-panel plot and absent in the single plot)

I agree with @mara that this will be a lot easier to debug if you can make it into a reprex! You seem to be pretty close. You would need to: