Hi @qliksus ,
I just did a quick check and I think the color-result when you select "Nation" is as expected.
In fact when you select nation State has not value
1. create a straight table
2. add dimensions like Geography, Geography Focus, Nation, State, TRx
3. then select Nation
== > see State value. So it will affect the expression used to color by "State" .
Review your model or try to use a default color when the color expression return null value "-"