Tooltip showing empty categories

Hi, i'm using a bar stack to show differents kids from their parents. The datas are ok with no empty lines because of the group by i'm using. But, when the tooltip cannot be fullfill, it's completed with empty kids from other parents. Do you know how i could prevent it ? I tried to test every bar stack options already, and i tried to change kids and parents data types from the admin pannel but it didn't worked.