I have resolved my issue by following instructions from this post View Underlying Data for Records with Unrecognized Zip Code
If any other has same problem as me, please also refer to the post above.
Thanks Deep, I have marked your answer correct as it may help others in the future...
Find my approach, Lets say you've below scenario.
I want to see list of 5 unknown countries.
1. Create a new sheet and drag the geo field on rows shelf.
2. Drag any one Longitude (generated) or Latitude (generated) tableau generated field on filters shelf and go to special and choose null values.
In this way you can get the unknown list.
Let us know If this help.
Hi Deep Kid,
Could you share the list of cities (and their country) that are failing to map in Tableau? I want to use this list to assess new data that we want to add to Tableau.
KentProduct Manager, Maps