Auth0 Login vs Signup screen hint not changing

When using the Auth0 plugin and “Login with Popup” action, the user is always being taken to a login screen, whether the “Screen hint” setting is set to “sign in” or “sign up.”

My understanding of the screen hint setting is that, if set to sign up, it should open an auth0 authorize window for sign up, not login.

Screen hint set to sign up:

What user is brought to (note they have to click the tiny “Sign up” link themselves to switch to sign up mode):

Am I misunderstanding the intended outcome here? Is there something else I need to configure to get the popup to open in the proper state?