type this in a command shell
wmic product get Name, Version
Is the software listed there ?
if not look at the registry under
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Uninstall
If the software listed in any of these places - ocs will report it
if it is not there try to disable inventory diff on server side
INVENTORY_DIFF Enable or disable differential inventory to speed up the server. With differential inventory, only changes are stored by the server, not full inventory.