When I import my CSV file, I can’t start the import process on the final step, the button is grayed out

This happens because the CSV file you’re trying to upload is either corrupt or doesn’t have the right encoding. The fastest solution for this issue is to:

1- Upload the file to Google Sheets

2- Download it back again as a CSV file

3- Try importing again

This simple trick makes the file have the right encoding and now you should have no more issues when importing.