LDAP authentication error, incorrectly identifying duplicate when none exists

HI, We're trailing the free version of Service Desk Plus MSP, we've had an issue where we get the following message while adding LDAP authentication to an account

Domain Controller with same name already exists. Please provide a different value.

After double and triple checking, there absolutely isn't another domain controller with the duplicate settings in the list of all accounts on the LDAP settings page.

Any suggestions on how to resolve this? The account is question was deleted and re-added as it wasn't able to be assigned to technicians correctly.