No indication that a purchase has been made

[NewTeslaUser]

In my app I am adding In App Purchase using this library.

This is what my activity code looks like:

public class InfoController extends AppCompatActivity {

    private static final String PREFS_NAME = "TEST_MyPrefsFile";

    private static final String FIRST_TIME_KEY = "TEST_isFirstLaunch";

    private static final String IS_PRO_KEY = "TEST_isPro";
    private boolean isPro() {
        SharedPreferences preferences = getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE);
        return preferences.getBoolean(IS_PRO_KEY, false);
    }

    private void setProUser(boolean isPro) {
        SharedPreferences preferences = getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE);
        SharedPreferences.Editor editor = preferences.edit();
        editor.putBoolean(IS_PRO_KEY, isPro);
        editor.apply();
    }

    private Button upgradeButton;

    String base64String = "xxxxxxxxxxxxxxxxxxxxxxxxxxxx";

    private BillingConnector billingConnector;

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

        upgradeButton = findViewById(R.id.upgradeButton);

        if (!isPro()) {
            upgradeButton.setText("Click here to upgrade to Pro");
            initializeBillingClient();
        } else {
            upgradeButton.setEnabled(false);
            upgradeButton.setText("User is Pro");
        }
    }


    private void initializeBillingClient() {
        List<String> nonConsumableIds = new ArrayList<>();
        nonConsumableIds.add("com.xxxx.pro");  // Replace with your actual non-consumable product ID

        billingConnector = new BillingConnector(this, base64String)
                .setNonConsumableIds(nonConsumableIds)
                .autoAcknowledge()
                .enableLogging()
                .connect();

        billingConnector.setBillingEventListener(new BillingEventListener() {
            @Override
            public void onProductsFetched(@NonNull List<ProductInfo> productDetails) {

            }

            //this IS the listener in which we can restore previous purchases.
            // Code will execute on InfoController.java appear. If pro is already purchased, unlock pro features.
            @Override
            public void onPurchasedProductsFetched(@NonNull ProductType productType, @NonNull List<PurchaseInfo> purchases) {
                String purchasedProduct;
                boolean isAcknowledged;

                for (PurchaseInfo purchaseInfo : purchases) {
                    purchasedProduct = purchaseInfo.getProduct();
                    isAcknowledged = purchaseInfo.isAcknowledged();

                    if (!isPro()) {
                        if (purchasedProduct.equalsIgnoreCase("com.xxxx.pro")) {
                            if (isAcknowledged) {

                                // CustomToast.makeText(InfoController.this, "The previous purchase was successfully restored.", Toast.LENGTH_SHORT).show();

                                // setProUser(true);

                                Toast.makeText(InfoController.this, "isAcknowledged", Toast.LENGTH_SHORT).show();
                            }
                        }
                    }
                }
            }

            //this IS NOT the listener in which we'll give user entitlement for purchases (see ReadMe.md why)
            @Override
            public void onProductsPurchased(@NonNull List<PurchaseInfo> purchases) {

            }

            //this IS the listener in which we'll give user entitlement for purchases (the ReadMe.md explains why)
            @Override
            public void onPurchaseAcknowledged(@NonNull PurchaseInfo purchase) {
                String acknowledgedProduct = purchase.getProduct();

                if (acknowledgedProduct.equalsIgnoreCase("com.xxxx.pro")) {

                    Toast.makeText(InfoController.this, "The purchase was successfully made.", Toast.LENGTH_SHORT).show();

                    setProUser(true);

                    upgradeButton.setEnabled(false);
                    upgradeButton.setText("User is Pro");
                }
            }

            @Override
            public void onPurchaseConsumed(@NonNull PurchaseInfo purchase) {

            }

            @Override
            public void onBillingError(@NonNull BillingConnector billingConnector, @NonNull BillingResponse response) {
                switch (response.getErrorType()) {
                    case ACKNOWLEDGE_WARNING:
                        //this response will be triggered when the purchase is still PENDING
                        CustomToast.makeText(InfoController.this, "The transaction is still pending. Please come back later to receive the purchase!", Toast.LENGTH_SHORT).show();
                        break;
                    case BILLING_UNAVAILABLE:
                    case SERVICE_UNAVAILABLE:
                        CustomToast.makeText(InfoController.this, "Billing is unavailable at the moment. Check your internet connection!", Toast.LENGTH_SHORT).show();
                        break;
                    case ERROR:
                        CustomToast.makeText(InfoController.this, "Something happened, the transaction was canceled!", Toast.LENGTH_SHORT).show();
                        break;
                    case ITEM_ALREADY_OWNED:
                        Toast.makeText(InfoController.this, "The purchase has already been made.", Toast.LENGTH_SHORT).show();
                        setProUser(true);
                        upgradeButton.setEnabled(false);
                        upgradeButton.setText("User is Pro");
                            break;
                    case ITEM_NOT_OWNED:
                        //TODO - failure to consume since item is not owned
                        break;
                }
            }
        });
    }

    public void onUpgradeButtonClick(View view) {
        billingConnector.purchase(InfoController.this, "com.xxxx.pro");
    }
}

When I am testing in app purchase I am using promo codes (since I do not have a card connected to my account).

So when I open up this activity, nothing shows up. I press the upgradeButton, the upgrade prompt pops up, I select promo code and type in the promo code, click next and it tells me that the price is 0 and I press confirm. After this, the purchase prompt window just closes and nothing happens. No Toast message shows up, the upgradeButton text still says: Click here to upgrade to Pro.

If I now close the app, open it back up and go to the InfoController (this activity), the Toast message isAcknowledged shows up.

So my question is: How come nothing happens after the purchase is done?
(When I open up the activity again after the purchase, it shows isAcknowledged?)

[NewTeslaUser]

@moisoni97 Any ideas?