Yesterday, the last things that I did were to create two new pages and modify the menus. Everything worked well.
This morning, I was advised to install both “Page Builder by SiteOrigin” and “SiteOrigin Widgets Bundle”, which I did. From that point, the bars at the bottom of the editor page (both Pages and Posts) overlay the content. See the screenshot for an example — you can’t see the content apart from most of the title and an image. Scrolling down allows me to see the content lower down, but not the content higher up.
I disabled and uninstalled both “Page Builder by SiteOrigin” and “SiteOrigin Widgets Bundle”, but this hasn’t helped. I changed the theme back to the default Twenty Nineteen, and disabled all of my remaining plugins, but the problem remains.
Might the two plugins have left some code or some database entries that could cause this problem? How can I be sure to completely remove every trace of the two plugins, please?