Have you tried installing the 39.2.1.5 version of Webex meetings. You can get it from here https://join-test.webex.com/webappng/sites/join-test/dashboard/download.
I have Windows 8.1 with the AnyConnect version 3.1.04072 installed. I have the SBL box checked but it is still not visible when I click Other User in the login screen. Please help.