Thank you for your suggestion, @James.Morrison. Unfortunately, I have already tried this and the result is the same as if setting it pr request from auth0.js. If I configure the connection to pass any non-empty value, this value is forwarded to the identity provider as expected. However, if I pass null or empty string, the empty value is not passed along, but instead the login_hint value is copied from the request to the login-page and forwarded to the identity provider.