You don't need to use sheet selector here to achieve the desired result.
You can create a single calculated field to display the required value as shown below:
And for the solution to your specific issue, you need to include a dimension to the columns. So, you can create a dummy dimension with no value, not null, and add it to the columns and suppress the header in each of the donut sheets and your issue will get resolved. Updated workbook 2 with this solution is also attached.
Hope this helps.
Thank you for your reply.
Yes , I know this methodology but i have to use sheet selector for my actual report because
I have to show actual number and % of total in the same sheet for Do nut chart.
Hope you saw the fix for your issue given at the bottom of my response above.
this did fix the issue. thank you so much. why did we have to add blank dimension? any thoughts?