The website is running WP v 3.4.1 and WordPress SEO v 1.2.5.
When an author link is clicked in a post’s meta: the_author_posts_link() it redirects to the homepage rather than the author.php or archive.php template.
This problem only occurs with the SEO plugin active and I cannot find a setting within the plugin that would affect this behavior. A search for this problem returned a resolved issue from 6 months ago that does not apply to this version of the plugin.
Apparently there used to be an Indexing > Archive Settings page within the plugin admin and a check box to disable the author archives, therefore, un-checking this box was the solution. However, I do not see this option in the current version and the author archives are definitely being disabled.