I've implemented the Xamarin.Auth sample code to authenticate with google's identity provider on Android. I'm successfully navigated to the Google login page using the device's Chrome browser where I can enter my credentials. I successfully authorize with Google but the Chrome Custom Tabs doesn't close when it redirects back to my app, i.e., I'm left looking at the google search in the chrome browser. If I close the browser I can see my app again with the user details returned from google's identity provider displayed.
Why is Chrome's custom tabs not closing on redirect from the Google identity provider, and how can I get it to close using Xamarin Forms and Xamarin.Auth?