I created a one-to-many join between a country polygon hosted feature layer and a contact point hosted feature layer. Wanting to create a list, in a dashboard, of all the countries where contacts were made, but I don't appear to have the Distinct expression written correctly...
The Advanced Formatting expression controls how the items are displayed, not which items are displayed.
To do what you want, create a one-to-one view.
@JasonCyphers, try looking at the Grouped Values table type. Use Country as the Category field.