Report Level Filter not displaying right info - need help.

Hi,

So I have created a report.  This report has a drill through working. Drill through is based on field A. There is also a report level filter on field B. When I select specific value in the drill through filter (in the visualization tab), I was expecting only relevant values to appear in the report level filter. However, the report level filter still shows all the values!

In the screenshot attached, the selected value for drill through is only ATCC.  Why still all the values appear for the Report Level filter? I was expecting it to dynamically change based on the drill through filter values selected!

The visualization change properly (the Line chart in this case) to show only ATCC values when it is selected in the drill through filter.  Can you please help? Thanks! Prashant-