After 1 and 2 success login to AzureAD, subsequent login cannot work

I used below code and nuget to login to my Paid Acct in AzureAD with Xamarin forms.

Nuget : Microsoft.IdentityModel.clients.ActiveDirectory

The subsequent attempts to login stuck at "Take you to your organization sign-in page".This means there is no result returned and the activity indicator kept running in circle or indefinitely.
Why cannot login again? Why I can login the 1st and 2nd attempts? I have used the correct parameters.

public interface IAuthenticationService
 {
  
Task<AuthenticationResult> Authenticate(string authority, string resource, string clientId, string returnUri);
 
}

private async void Login_Clicked(object sender, System.EventArgs e)
{

   var authenticationService = DependencyService.Get<IAuthenticationService>();

 try
 {
    var authenticationResult = await authenticationService.Authenticate(
    AuthenticationParameters.Authority,
    AuthenticationParameters.GraphResourceUri,
    AuthenticationParameters.ApplicationId,
    AuthenticationParameters.ReturnUri);

                if (authenticationResult != null)
                {
                    var strToken = authenticationResult.AccessToken;
                     
                    await DisplayAlert("Success", strToken, "Ok");

                }

 }
   catch(Exception ex){

     string strErr = ex.ToString();
     await DisplayAlert("Failure", "Authentication failed.", "Ok");
     }
  }

Please help. 

Thanks