Hi VaraPrasadraju,
What you are facing is a known issue in Design Studio. While a filter is applied on the list of countries, a 'getMemberList()' function will still get all the members for the mentioned dimension regardless of the filter you have set. The RBU list, however, will reflect the filter set on the country because it is dependent on that country - i.e. each RBU value would be associated with a country, and thus only the RBU value for the country selected is retrieved.
Thanks and Regards,
Eshwar Prasanna