To fix this issue, install the December 6, 2016, update (KB3127976)
for Skype for Business 2015 (Lync 2013). If the Options
dialog box is opened before the client has connected in background to the Persistent Chat server, the Persistent Chat
section of the Options
dialog box will now warn the user that "Persistent Chat settings will be available later." Note
Lync 2013 was upgraded to Skype for Business in April 2015.