This feature is only available for Business plan. This happens if a signer in the csv has missing or invalid data. The CSV file should have two columns  with headers "name" and "email". Each row below these headers represents a new signer where you should add the signer's name in the "name" column and a valid email address in the "email" column. If either of the data is missing or the email is invalid for a specific signer, this will result in the invalid status for that signer after the CSV file is uploaded.