Welcome to the Auth0 Community! Answering this since it might help others as well!
This issue is usually triggered by mobile browsers which tend to block redirects when using an https scheme leading to a “Not found ” or blank page. Given that you are trying to integrate this with your Android App the solution should be using any custom scheme that is not http or https in the callback URL.
You can also follow this Knowledge Article that provides links to working code examples.
Best regards,
Remus