only authenticated role merges to mailchimp field

Our Mailchimp list has a field that is supposed to receive its content from the user's role in Drupal -- in Drupal in list management area under "Merge Fields" this particular field is set to take its data from the users' role. However, only the 'authenticated' role is being synced over. All roles were syncing from Drupal to Mailchimp a couple months ago, but this mysteriously isn't working now. Considering that, I don't assume this is a bug, but I have no idea how to get this working properly. Authenticated merges, but none of the others...