WebAuthenticationBroker API prompt login with blank page

[headsea]

In WinUI3 UWP app, when to use Windows.System.Launcher.LaunchUriAsync(uri), it will open system browser then redirect to https://auth.xxx/login to allow user to input user/password. But when to use Windows.Security.Authentication.Web.WebAuthenticationBroker.AuthenticateAsync( Windows.Security.Authentication.Web.WebAuthenticationOptions.None, uri), it will open webauth dialog with blank page, checked with Microsoft-Windows-WebAuth/Operational event log, it shows navigation complete: AuthHost completed document from URL: https://auth.xxx/login/.

uri: https://auth.xxx/oidc/endpoint/xxx/authorize?prompt=login&response_type=code&client_id=xxx&redirect_uri=xxx&scope=openid%20openid%20general%20profile&state=xxx&code_challenge_method=S256&code_challenge=xxx
(OpenID Connect Indentity Provider)

Appreciated who can help clarify why WebAuthenticationBroker not work in this scenario?