I found that the new code did not work on your site, even though it worked on my development site and several of my websites. Could possibly be the version of PHP you have, or some interaction with a plugin.
But I reworked the primary code, and will try to post Version 4.3.6 later today, or possibly tomorrow. Have one last Block Editor styling issue to fix, and it should be ready.
I could not have fixed this obscure issue without your help – thanks so much. I really don’t understand exactly how my code fixed the issue, but it seems okay now. I did direct tweaking on the files of your staging site, so it works. But you should upldate to 4.3.6 when it is released.