November 13, 2013 Update: the presence issues with Exchange free/busy that were introduced in the September 2013 Lync 2013 Client update have now been fixed in the November 2013 Update; see Lync 2013 November Update – A Much Anticipated Client Fix.
Recently there as been many reports of Presence issues with the Lync 2013 client. Here is a breakdown of three major known issues and what to do about them.
Exchange Integration Issue Introduced in the Lync 2013 September 2013 Update
The most common problem was introduced in the recent September 2013 update package for the Lync 2013 client. The issue is documented in this support KB article: Presence . . . → Read More: Lync 2013 Presence Issues