Null Values in Drill Down Group

[nate_eyster]

All,

I have a 3-tiered Drill Down Group, the image below is showing the 2nd layer, displaying products after selecting Oncology. Product 05, 07, and 06 belong to a different group in the first tier that was not selected. Why are these values still showing (grey)? Is there anyway to hide these or is this how drill down dimensions work within in sense?