Incorrect Cities: GA4 Data Map of Users by City, Filtered by Region showing incorrect cities.

[nathelpdesk]

I am creating website analytics visualizations (using GA4 and a report on Looker Studio) for an organization focusing on Massachusetts clients. We're trying to understand where our users are coming from, so I am attempting to make a map of cities in MA, colored by the number of users in each city.  

I did this by using the Filled Map, with "City" as the location field, Total Users as the color metric, and applying a chart filter of: "Include > "Region"  > Equal to (=) > "Massachusetts"

The result is a map that includes most cities in Massachusetts but for some cities in which another city on earth uses that same name, the city appears only in its location outside Massachusetts.  For example, Cambridge England appears as a data point on the map (with a high number of users, as we would expect Cambridge MA to have) but Cambridge MA appears blank on the map. There is no city outline on the map at all. Similar things happen with Watertown NY, Hamilton Ontario, Hanover Germany, etc. 

What's going on here? Is there any way to have all of these data points align to the Massachusetts city with that name?