Android studio facebook login button - nothing happens after clicking login button

Question

First off, I am a true beginner to Android studio and to Java so please bear with me.

I am following a you tube video explaining how to use Firebase to allow user authentication using facebook log in. I have done my best to repeat what was outlined in the video but when I run the app and click the "continue with facebook" button it brings up the facebook popup saying "Continue as XXXX" screen and after clicking on continue nothing further happens. The facebook pop up screen disappears but nothing happens - there is no confirmation the login was successful (I expected the button to change to "log out" and another activity to start) and no confirmation that log in failed. Is there anything obvious I am missing in my code or a setting? I've included my code below.

I have enabled "login from devices" on facebook for developers as per advice from a similar thread on SO. But that did not seem to work.

package com.example.firebaseauthapp;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.widget.Toast;

import com.facebook.AccessToken;
import com.facebook.CallbackManager;
import com.facebook.FacebookCallback;
import com.facebook.FacebookException;
import com.facebook.FacebookSdk;
import com.facebook.login.LoginResult;
import com.facebook.login.widget.LoginButton;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.auth.AuthCredential;
import com.google.firebase.auth.AuthResult;
import com.google.firebase.auth.FacebookAuthProvider;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;

public class MainActivity extends AppCompatActivity {

    private CallbackManager mCallbackManager;
    private static final String TAG = "FACELOG";
    private FirebaseAuth mAuth;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Initialize Firebase Auth
        mAuth = FirebaseAuth.getInstance();

        // Initialize Facebook Login button
        FacebookSdk.sdkInitialize(getApplicationContext());
        mCallbackManager = CallbackManager.Factory.create();
        LoginButton loginButton = findViewById(R.id.login_button);
        loginButton.setReadPermissions("email", "public_profile");
        loginButton.registerCallback(mCallbackManager, new FacebookCallback<LoginResult>() {
            @Override
            public void onSuccess(LoginResult loginResult) {
                Log.d(TAG, "facebook:onSuccess:" + loginResult);
                handleFacebookAccessToken(loginResult.getAccessToken());
            }

            @Override
            public void onCancel() {
                Log.d(TAG, "facebook:onCancel");
                // ...
            }

            @Override
            public void onError(FacebookException error) {
                Log.d(TAG, "facebook:onError", error);
                // ...
            }
        });

    }

    @Override
    public void onStart() {
        super.onStart();
        // Check if user is signed in (non-null) and update UI accordingly.
        FirebaseUser currentUser = mAuth.getCurrentUser();
        if(currentUser != null){
            updateUI();
        }

    }

    private void updateUI() {
        Toast.makeText(getApplicationContext(), "You're in", Toast.LENGTH_LONG).show();

        Intent accountIntent = new Intent(MainActivity.this, AccountActivity.class);
        startActivity(accountIntent);
        finish();
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        // Pass the activity result back to the Facebook SDK
        mCallbackManager.onActivityResult(requestCode, resultCode, data);
    }

    private void handleFacebookAccessToken(AccessToken token) {
        Log.d(TAG, "handleFacebookAccessToken:" + token);

        AuthCredential credential = FacebookAuthProvider.getCredential(token.getToken());
        mAuth.signInWithCredential(credential)
                .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
                    @Override
                    public void onComplete(@NonNull Task<AuthResult> task) {
                        if (task.isSuccessful()) {
                            // Sign in success, update UI with the signed-in user's information
                            Log.d(TAG, "signInWithCredential:success");
                            FirebaseUser user = mAuth.getCurrentUser();
                            updateUI();
                        } else {
                            // If sign in fails, display a message to the user.
                            Log.w(TAG, "signInWithCredential:failure", task.getException());
                            Toast.makeText(MainActivity.this, "Authentication failed.",
                                    Toast.LENGTH_SHORT).show();
                            updateUI();
                        }

                        // ...
                    }
                });
    }

}