There is no drill down capability for the tree in the Task Pane.

I would like to understand better what you are looking to do with the drill down feature as part of the tree.  Please reach out to me and we can correspond or discuss [email protected].  I would like to add your request to our list of features for the product team and one of the questions from the team has been what is needed for the Tree feature.  I hope to hear from you.  Thank you, Sandra.