Salesforce Connector Sync Issue

When I try to sync form responses from sitefinity 9.1.6110.0, I get the following fail message.

You don't have SalesForce external id field. Please go to your SalesForce account -> Setup -> Customize -> Contacts/Leads -> Fields and create a new text field with unique values, 36 characters minimal length and set it as external id. Then enter its name in the Sitefinity Advanced settings -> SalesForce connector.

I have tried using both, the field name and api name on the administration -> Salesforce Connector -> salesforce account -> Leads external id

I restarted the application pool each time I updated the field name in sitefinity, the mapping can see the field(API Name), Login is successful, Attached is a snapshot of the Salesforce field screen.

Any ideas on what may be happening or where to look would be greatly appreciated.