I'm seeing across multiple API management instances, then when I disable signup (https://docs.microsoft.com/en-us/rest/api/apimanagement/2020-06-01-preview/sign-up-settings/update#request-body, properties.enabled = false), then signup is effectively blocked as expected. But unfortunately I'm also no longer able to sign in to the developer portal with neither a new (invited) nor an existing user. Instead I'm getting am "Please provide a valid email and password". If I invite a new user, and that user opens the invitation link and sets the password, then the user is actually logged in. If that user then logs out, then he is not able to login again.
I have observed that the "Username and password" provider (Developer portal | Identities) is removed, when I set the enabled = false. Likewise the provider appears again, when setting enabled = true.
Am I doing something wrong, in order to achieve "invite-only" behavior in the developer portal?