I'm looking at this.
This is really weird. I think something is corrupted in your Headcount by Category sheet.
First off, the way you set up that action should work.
I tried deleting that sheet from the dashboard. I got a message that it was hidden (even though it was not). So I clicked unhide. And Tableau deleted it. Then I tried re-adding it to the dashboard. It went onto the dashboard, but showed no data. Go back to the actual sheet, and it displays as expected. DUPLICATE THE SHEET, and the new copy comes up empty.
Try to figure out what's happening with this sheet. Maybe rebuild it and use the new one.