Hi All,
Finally Managed to resolve the issue.
As the CM was not able to find the CurrentSiteVersion, I did a search on registry to see if the current site version is available anywhere and the result was none.
So I had to manually add the site version on registry in the following path
HKLM\Software\Microsoft\SMS\Setup\Full version
Please note when you add the version entry, you have to match it with the format same as in the hman log as the 'about' information in the console shows only 5.0.8xxx.xxxx (you need to add additional '0' after 5.0 (eg:5.00.8412.1000)
Once you done this, restart sms_executive service and the updates will be available instantly in updates and servicing node.
Happy imaging!!!