Can you share your page structure to view your design ?
As Ronald Suggested, Please check the microflow via debugging to find the existence of objects.
You dont need a microflow to achieive it. Create a page with layout grid dividing in to two equals.
Keep Listview in First half of the layoutgrid.
Keep dataview in second half and Data source type of the dataview to Listen to widget and select the listview. Then inside the dataview, Place the datagrid & chose association ( which holds the country details data ) as a datasource to view country detail record
Did you set a breakpoint in the microflow after the retrieve to check if there was an object? Did you create a new object if the object was empty and attached it to the country record?
And you do not have to use a microflow. You could also just open the page that has the details entity as parameter.
And do note that there is a country module in the appstore with all the countries: https://marketplace.mendix.com/link/component/1775
Thank you Ronald and Arun.