Yes, the link I sent is an established blog post from many months ago. I didnt’ want to publish a test blog. But I just figured out how to keep it off my site and still let people on this forum see it. Here’s the link to the blog that isn’t working correctly: https://figuringoutmelody.com/3ns-field-guide-tester/
I put two versions of the “Lean On Me” example in this blog with the same code. To test that they were indeed the same, I copied that code from the WP editor and re-pasted it into Word with the paragraph and space marks visible. Here’s a screen shot:
As you’ll see from the actual blog post, the two examples display differently.
I am no html or WP expert. There may indeed be the sort of trouble with WP receiving my pasted “plain text.” For example, I noticed that the earlier version of this post, which had the same issues, replaced my paragraph breaks with line breaks. I went through and made them all true paragraph breaks, but as you see here, that did not solve the trouble.