NEW NEWS! I found something else my problem profiles have in common. I edited all of them on 7 Dec 2019, and that's just days before Chris Whitten announced the new Comments protocol. No doubt work was ongoing on 7 Dec. So the problem could be connected.
ALERT! I suggest anyone who was editing on 7 Dec 2019 should examine their profiles just in case. If there's this problem, then in the logged-off mode you can see it at once because the space below the padlock on the right is very blank. Then you'll find your links don't link. But then if you log in, the profile looks normal.
Also I took a look at the HTML code for my profiles. At the first glance, the DOCTYPEhtml for a healthy profile looks about twice as long as for an unhealthy one. All the lines from <! - - end wrapper... down to above the line <ins class... seem to be missing from an unhealthy profile. (In the logged-off mode, this is.) Exploration revealed that the missing lines are hidden under the <div class="wrapper"... heading instead of being on the same level with it. Also some lines of the <div class="wrapper" itself appear to be missing.
So I'm guessing that's at least part of the problem. I'd rather let one of you experts clean it up than try it myself. Hopefully someone can take a look at this soon, yes? Chris did say that the new Comments protocol might cause problems, and I think this is one.
The profiles in question are: Layton-1810, Layton-1915, Layton-1927, Layton 2011, and Layton 2019.
Thanking you in advance, Pauline Layton-1804