First thing, a very nice visualization.
- I think the issue is the filed you are using while setting up actions.
- You can select on which fields you want the action to be working.You can read more about them here - Filter Actions .
- Point 9 from the above link shows all fields and selected fields where all fields is usually the default.
- Change this to selected fields and click on add filter to select the age related field.
Hope this helps.
My source (the donut) charts use Measure Values as the field, but that doesn't show up as an option in field area of the filter option box. Does that mean I have to reorganize by data in a way that makes age group a single field?
As far as I know you cannot use measure values in the filter action. Workaround would be pivot your measure, set up your view, and then create the action.