I have a similar problem with https://banno.com/a/oidc-provider/api/v0/auth, which is returning the response below. My client id is 05815133-6c9e-4fa0-9e53-d56b753d1800. I'm using the Node sample application for this test.

{"error":"invalid_client","error_description":"client is invalid","state":"f2pg3di9cdh9h3luvopcf","iss":"https://banno.com/a/oidc-provider/api/v0","request_id":"8f4b1950351fc5eca23a55d5b0548314"}