Consider the following scenario:
You deploy a Persistent Chat server in a Microsoft Lync Server 2013 environment.
You add a distribution group (DG) as a chat room member in the Lync Server 2013 environment.
A user in the DG signs in to Lync 2013.
In this scenario, the user does not receive chat room invitations. Additionally, users in the DG cannot join the Group Chat room.
This issue occurs if it takes longer than expected for the Persistent Chat server to synchronize with Active Directory Doman Services (AD DS).
To resolve this issue, install the cumulative updates that are described in the following articles in the Microsoft Knowledge Base:
2835432 Description of the cumulative update 5.0.8308.420 for Lync Server 2013, Core Components: July 2013
2835433 Description of the cumulative update 5.0.8308.420 for Lync Server 2013, Persistent Chat: July 2013
2835435 Description of the cumulative update 5.0.8308.420 for Lync Server 2013, Web Components: July 2013
For more information about issues that affect user particiaption in chat rooms, click the following article numbers to go to the articles in the Microsoft Knowledge Base:
2783949 User in a DG does not receive a chat room invitation when the user signs in to an Office Communications Server 2007 R2, Group Chat client
2796758 User cannot join a Group Chat room after you add the user to a DG that is a member of the Group Chat room in a Lync Server 2010 environment