Custom Shape Map - Insert City Polygon in State County Map

Hello,

I am trying to display City of Detroit along with Counties in Michigan map. I have downloaded and imported the City of Detroit shape file and Michigan Counties shape file to Mapshaper. I have merged 2 layers using "merge-layers" command in Mapshaper console. I was able to see the City of Detroit boundary under Wayne County of Michigan map in the output of merged file.

I have exported the output in TopoJSON format as a local file. I have converted the output coordinate system to WGS 1984. But, when I loaded this custom map to Shape Map visual in Power BI, I am not able to find the City of Detroit's boundary in Power BI. It is displaying the whole Wayne County with out Detroit polygon.

I have checked Map keys. It is fine. When I filtered City of Detroit in my fields, the Shape Map is approximately zooming in to Detroit's geographic location in default grey color. 

I need to display boundary for City of Detroit to appear so that one can select Detroit or rest of Wayne County in Power BI Shape map.

Am I missing some steps to be done in Mapshaper? Can you please help me with this?

I am sharing the source file download links below,

http://gis-michigan.opendata.arcgis.com/datasets/cities-v17a/data?where=NAME%20%3D%20%27Detroit%27

http://gis-michigan.opendata.arcgis.com/datasets/counties-v17a/data

Power BI Desktop Version: 2.84.861.0 64-bit (August 2020)

Windowns Version: Windows 10 Enterprise

Thank you,

Abhinav