Inrecently encountered an error on wsus server running on OS 2012 R2. The KB3159706 was the cluprit. There are some manual configuration agter installing this update.
Go to c:\program files\update services\tools\wsusutil.exe postinstall /servicing. Wait for a few minutes.
Restart wsus service
Remove wsus from %appdata%\microsoft\mmc
The wsus console should now be working.
This solved the issue for me. Hope this helps someone.