Upgrade from 4.5.8 to 4.6.2 killed View Contact Tabs
Aaahhhh!!!! I just noticed that this client's Drupal user ID was set to view the site with the default Garland theme whereas my Drupal user ID was set to view the site with the custom theme built for this site. I switched the client's Drupal user ID to use the custom theme, and now AJAX refreshes correctly. So, it appears Drupal Garland theme specific.