It seems that Ed Braxton is the top customer for Akron city.
Data blend and LOD are used in my approach.
Please refer to the attached workbook for details.
Sample workbook.twbx 919.2 KB
Is there a reason why when you filter out customer name you still want to it in the map?
If you've got this map on a dashboard, you could change the filter so that it doesn't affect the map at all:
Also, from your attached workbook, I can't seem to find a top N name calculation.
I've added in a rank calculation in my attached sample workbook so that you can check out how to work out the top customer name.
Max Customer ID.twbx 7.5 MB