I finally got the pages to look right, but the compromise is that the slug has to stay as “sermons”. I have a page named “messages” that uses shortcodes to produce the desired layout for the archive listing. The individual sermon pages come under the slug “sermons”. If I change the Archive Page Slug setting to anything other than sermons, the individual pages appear to no longer be governed by the Sermon Manager plugin, other than to be published.
Can you explain more about how you made this work for you?