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 status isn’t updated based on Exchange calendar in Lync 2013.
First and foremost Microsoft has delivered, in two separate stages, the ability for Skype for Business 2016 Windows clients to leverage VBSS in conferences now.
As covered in the previous article when this new capability was released in 2015 it was only available for peer-to-peer Desktop Sharing sessions between to 16.x version Windows clients.
Whilst you might start with a patched Lync 2013 Client, it’s replaced with the brand new Skype for Business client.
In the meantime uninstalling the September 2013 Update and/or rolling back to the August 2013 Lync update resolves the issue.
Until Office 2016 is released, THIS is your client-side update path to Skype for Business: Install Lync 2013 from Office 2013 and then patch it with this (or a later) update & the necessary pre-req’s.
You will also use this patch to turn your “Lync Basic” client into a “Skype for Business Basic”. If you want to manage the rollout of this internally via SCCM or WSUS, the two KBs you’re interested in are these: There are no fixes here as applying this patch is installing a brand new client.
Today marks the release of the new Skype for Business Client update to Windows Update.
Much has been written in anticipation of this of late and there are plenty of references I’ve captured below.