Users not being auto-added to confluence-users group

After upgrading from 2.10.3 to 3.1 the configuration change we had made which auto-added users who login (we are pulling credentials from our onsite AD server) to the confluence-users group no longer appears to be working. I made the same change to the seraph-config.xml file that we made in 2.10.3 to ensure that this login hook worked but it does not appear to be working. The link we added/changed was

<authenticator class="com.atlassian.confluence.user.ConfluenceGroupJoiningAuthenticator"/>

For users that already had been made a member of the confluence-users group this does not appear to be an issue it is only causing new users issues.

Any ideas?