A new behavior - I don't know what I changed to have caused it.
I have set the title and read more as links to the full article. It worked beautifully. Now when I select a title or read more link the article opens on the frontpage rather than on its own page.
It looks like the menu item the articles used to fall into is disabled or removed. Articles open on the front page if they have nowhere to go particularly. If you use module instances, you can force the menu item id.
Simplify Your Web is not affiliated with or endorsed by The Joomla! Project™ or Open Source Matters. The Joomla!® name and logo is used under a limited license granted by Open Source Matters the trademark holder in the United States and other countries.