Drill Down OTBI bar chart report is not working correctly using several columns

Summary:

We have a master report which has the following columns: -Positioning Before, Grade Code, Gender, Number of eligible employees. I used a stacked vertical bar chart to represent the data. I have also created a detail report which has the following columns: Person number, First name, Last name, Grade Code, Gender, Positioning before, etc.. Ideally, on clicking on the yellow section of the bar chart as below, the master report should drill down to the detail report to show only 4 records for the eligible employees as shown on the hovered bar.

Initially, the drill down action was on the "Positioning Before" column only and the detailed report showed all the eligible employees with "Positioning Before" having the value "Within" as indicated by the yellow bar. However adding the drill down action on additional columns, i.e. "Gender" and "Grade Code", two buttons appeared instead - One for "Positioning Before" and the other for "Grade Code" and "Gender". We want to know on how to have a single button for which the drill down includes the three columns to filter/drill down on. Results when clicking on the hovered bar(from screenshot) should display the