Scope

Bulk operations - Map unmatched CSV columns from dropdown
The columns are not mapped correctly in the CSV template file. 

The data is merged under one column in the CSV file. 

Summary

The issue generally happens because of the regional settings. In some countries (like Denmark) they use ";" to separate tabs in .csv by default rather than "," and that tricks the system.

Solution

On Microsoft Excel, Navigate to settings > language > related settings > administrative language settings > formats > additional settings > and change "list separator" to ",". Then you have to save the .csv as a new file (replace the old one) and it shall work as expected.