When clicking on any of the options/menus available under Symantec Installation Manager (SIM) main page, like "add/Update licenses" or "Configure settings", nothing happens. Clicking on those menus does nothing and the expected pages do not open.
ITMS 8.1 and later
SIM was out-of-date. In this particular scenario, the SIM was 4 versions behind the current SIM version.
Upgraded SIM to the most recent version.