The customer reported that when he clicks on any of the options/menus available under Symantec Installation Manager (SIM) main page, like "add/Update licenses" or "Configure settings", nothing happens. Looks like clicking on those menus do nothing, the expected pages doesn't open.
ITMS 8.1 and later
SIM was out-of-date. In this particular scenario, the customer was 4 SIM versions behind what was current for SIM. In this particular case, the customer had SIM 8.5.3025 installed when the most recent was 8.5.4220.
SIM versions between what the customer had and what was the most recent:
8.5.3700 / 8.5.3701
Upgrade SIM to the most recent version.