If you know something works when you put it in the HTML editor, compose the post in the Visual one if you want, then just before publishing go to the HTML editor and change it there. Don’t click back to Visual, just hit Publish. That will keep it in place.
Thanks for your replies.
One of the WP support people put the in for me and said it worked. Of course, when I went back later it was stripped. For some reason this issue seems to have little interest, but for those of us who cannot get a bonifide fix, it is on the top of our list. Of the many true WP experts, would one please end this quibble by sharing the fix for it?