Why is nothing being imported?

First, please refer to both the CSV File Setup Requirements and the Tips sections in the documentation as following those resolve most issues encountered when attempting to import a CSV file.

If you are importing an exported file into a “clean” or “empty” database, do not map the Entry ID when importing. Mapping the Entry ID column tells the CSV Import to update the existing entries. If those entries do not exist, there are skipped, they are not imported as new entries.