Google map – Using Javascript API – How to highlight disputed countries

We are a nonprofit organization who would like to highlight all the countries where we sent our donations, including countries with disputed borders, like Kosovo.

We are using the Google Maps Platform with the Javascript API.
We use the feature layer “Country” to change the style of selected countries.
Everything works fine for countries that are not disputed.

We tried to use the same pattern for disputed countries that we use for other countries but with no success. We are unable to change the style of disputed countries and we can’t even listen to the mouse-over event for displaying a proper tooltip.

Is this can be done ?
Any suggestions on how we can do it using google map ?