This could be because the CSV tool did not match your input correctly in the Match Columns page.
If you are:
Directed to the Review Entries page immediately after uploading the file and
See a lot of errors (like below) prompting you to select an option even though you have those options in your file:
Click the Back button > and click Go back to return to the Sheet Selection page
Scroll down and make sure all the parameters on the left match successfully with those on the right. Below is an example of an input that failed to match automatically:
From the dropdown, select the correct value to match:
Click Confirm and proceed as usual. The error rows would be removed in bulk.