Xamarin Form IAP error the application is not configured for billing through Google Play

I am receiving the above error [0:] Error: Plugin.InAppBilling.Abstractions.InAppBillingPurchaseException: Unable to process purchase.

I am using Plugin.InAppBilling library.
My code looks like this.
public async Task PurchaseItem(string productId, string payload)
{
var billing = CrossInAppBilling.Current;
try
{
var connected = await billing.ConnectAsync(ItemType.InAppPurchase);
if (!connected)
{
//we are offline or can't connect, don't try to purchase
return false;
}

                //check purchases
                var purchase = await billing.PurchaseAsync(productId, ItemType.InAppPurchase, payload);

                //possibility that a null came through.
                if (purchase == null)
                {
                    Console.WriteLine("Purchase canceled!");
                }
                else if (purchase.State == PurchaseState.Purchased)
                {
                    var id = purchase.Id;
                    var token = purchase.PurchaseToken;
                    var state = purchase.State;
                    return true;
                }
            }
            catch (InAppBillingPurchaseException purchaseEx)
            {
                //Billing Exception handle this based on the type
                Debug.WriteLine("Error: " + purchaseEx);
            }
            catch (Exception ex)
            {
                //Something else has gone wrong, log it
                Debug.WriteLine("Issue connecting: " + ex);
            }
            finally
            {
                await billing.DisconnectAsync();
            }
            return false;
        }

For info all the below are checked

AndroidManifest must include "com.android.vending.BILLING" permission.
APK is built in release mode.
APK is signed with the release certificate(s). (Important: with "App Signing by Google Play" it only works if you download directly from GooglePlayStore!)
APK is uploaded to alpha/beta distribution channel (previously - as a draft) to the developer console at least once. (takes some time ~2h-24h).
IAB products are published and their status set to active.
Test account(s) is added in developer console.
My testing app is the same that is currently published in the Play Store