Cannot signup with username password when enterprise connection is defined

I have a problem somewhat similar to This domain has been configured for Single Sign On you can't create an account

My client is configured with two connections: Username-password db, and Azure AD. The first is used for customer login, where as employees login with Azure AD.

Some employees are also customers and would like to sign up as a customer using their corporate email. Unfortunately, they cannot sign up with their corporate email. The error {"code":"signup_on_sso_domain","domain":"","error":"This domain has been configured for Single Sign On and you can't create an account. Try signing in instead."}

I understand the reason for this error message: The corporate email domain is registered in the Azure AD connection and Auth0 believes this connection should handle all login/signup with this email domain.
What I dont understand is why I cannot override this behavior when I am explicitly specifying connection in the signup-call:

   connection: databaseConnection, //The id of my username-password connection
   email: email,
   password: password

Any help is much appreciated

Hi, We ended up opening a support ticket on this matter. I can share the support information that we got if you’d like, but in the end we ended up not solving this problem, instead we made another agreement with our client.

Is such a thing impossible with Auth0

I don’t know, I think there are workarounds, but we decided that it was too time consuming to look further into, so we did another agreement instead. I have PM’ed you the response that I got from support, I’m not sure if they like it publicly available so I wouldn’t post here, and i’m not even sure it will be of any help but it’s all I can do. Please share your experience here if you manage to get to the bottom of this issue.

Best of luck!