Mobile app is configured to work with one domain where UNA is installed. All other URLs should be opened in external browser. So it maybe this cause such behaviour in Android app, if you want to allow some additional domain you need to add other domains in App.js file:

        var aExceptionsUrls = [
            'redirect_uri=', 'redirect_uri%', 'redirectUri%', // Facebook/LinkedIn Connect and other Connect apps
            'signin/oauth', 'signin%2Foauth', // Google Connect
            '/m/oauth2', // Dolphin/UNA Connect
            'api.twitter.com', // Twitter Connect
        ];