Assume that you install June 7, 2016, update for Lync 2013 (Skype for Business). Then, you join a meeting without audio devices. In this situation, a blank window is displayed. The expected scenario is that you receive a message that indicates that you can't join the meeting because of no audio device.
To fix this issue, install the September 6, 2016, update (KB3118281) for Lync 2013 (Skype for Business).
Note Lync 2013 was upgraded to Skype for Business in April 2015.