How to make the Authentication Managed Server Flow to work in Android

Hi:

I follow this article without luck for the Android with Azure AD B2c configuration (easy auth in app service):

https://developer.xamarin.com/samples/xamarin-forms/WebServices/TodoAzureAuthADB2CServerFlow/

My problem is that when I hit the login button, a web page, the following message is displayed:

"you have successfully signed in"

But the sign in dialog page was never displayed.

Also this page is not closed automatically as I would expect, I mean to return the control to the Xamarin app.

Any idea why this Server managed flow is not working. When I tried the client flow sample, the authentication process worked fine.

Thanks in advanced

David