I have an external content type which has two operations defined. When I try to open the operation of type "Read List" from SharePoint Designer, I get a credential challenge and when I enter credentials for any of the service accounts, I get the following error:
Message from external system: login failed for user 'xxx'
When I navigate to the Manage Service Applications > Secure Store Application, I can see the Target Application ID but not sure how to confirm which service account I need to use to login from SharePoint Designer.
Any pointers?