Troubleshooting Salesforce Account Owner Field in Clay Table Append

currently running into an issue when trying to append a clay table of accounts with salesforce account owner data...when i select the "lookup record" action, i'm prompted to fill out these fields: salesforce object (i'm choosing account), object fields (i want to select account owner, but its not populating as an option), and the final field is "____ to search for" where the blank is populated with the field i selected in the previous prompt i.e. account owner to search for. Can anyone help here? why might 'account owner' not be populating in the object field? whats the best practice for appending clay table data with salesforce account owner data?