I think I know what happened. With previous posts I published from Ulysses I did not enable markdown in the publishing dialog and therefore the publisher converted the markdown to HTML so it appeared correct in Wordpress. In the previous post I enabled markdown, and since Wordpress was not configured to use markdown it did not render properly. So, to have enabled markdown in the writing settings of the WP-Admin console, which fixed the problem.
In other words…. operator error! :)