Thank you. Updating the theme fixed the issue.

For the record, the Theme Update tab showed that no update was available. I don’t know if that was a bug or not, but I’ll keep an eye out for manual updates from now on.

Also, your link to documentation (kriesi.at/documentation/enfold/updating-your-theme-files/) does not lead anywhere.

Admin details attached in private content.

I installed and activated the plugin, but it doesn’t seem to make any difference. Many images and links are still using http.

For example:
https://smasolutions.it/contact-us/

The image on the page is called using http, not https. This only seems to affect some images and links on some pages, though.

Any ideas?

Perfect! Thanks for the help!

The widget is called ‘Sidebar Navigation’

It creates a list of all pages within that section (child, parent and sibling pages).

It appears in the Available Widgets list, but as soon as I move it to a widget area, it disappears from the Available Widgets list so I can’t use it again. I can use it in the ‘Displayed Everywhere’ widget area, but I would like to only use it on some pages.