Meta info: I replied in another thread that was about this exact topic, but I did not get a reply. I suspect that I was wrong to thread hijack. I then tried to start a new thread by copying and pasting from my first reply, and that went terribly wrong. So I’m starting a third time, retyping it. Sorry for my earlier mistakes.
I am having trouble configuring TinyMCE. I’m using an override of the blank theme. In Publii/my-site/input/themes/blank-override I have the following config.json: