Zoom on Shape Map Incorrectly Changes Conditional Color

Hello!

I have a US-county shape map set up with conditional color rules - based on a % score for each county, the colors range from white (0%) to dark purple (75-100%). The conditional formatting works perfectly at the national level:

The coloring also works perfectly when auto zooming to a state with varying county-level % (this is TN):

However, when zooming in on a state where all the counties score 0, instead of making the entire state white, all of the counties default to the 75-100% color (this is Maine, which as you can see properly displays as all white in the national map):

Any ideas why it does this and if there's a workaround? Thanks.