Issue
Sending to DocuSign with Recipient Secure Fields an Error occurs due to a List not being configured with specified values.
Error Code
An error has occurred. (InternalError)
Parameter name: listItems - Value cannot be null.
Resolution
Navigate to all Recipient Secure Fields and verify all List Item types have values listed for Signer Selection on the DocuSign Side.
Additional Information
Documentation: https://help.nintex.com/en-US/docgen/docservices/#docgen-sfdc/Services/manageDDP/CreateSecureFields.htm?