Hi All ,
Just wanted to update the issue with this resolution :
The settings were missing in the web.config in the ReportManager folder.
After we made the change and restarting the SSRS Service , I were able to make edits to the Subscriptions .
However , I am not sure as to why the number of rows column would be different form what we see in the report or the output of backend query. Where as the extended info shows correct number of rows.
RowCount = 23894 in ReportServer DB
where as teh AdditionalInfo xml is this :