The purchase dialog does not show up since iOS 13.4

Question

Since iOS 13.4, the dialog for in-app purchases does not show up when the line...

[[SKPaymentQueue defaultQueue] addPayment:payment]; 

...is executed.

Pre iOS 13.4 a dialog popup showed up where the user confirmed the purchase, but now nothing. Does anyone know what might be causing this issue?

Notes:

• It's a fullscreen game based upon libSDL and gles 3.0.
• While 99% of the code base is C++, the in app purchases is made in Objective C++
• It worked before iOS 13.4

Answer 1

try to totally "flush" the queue once:

    - (void)paymentQueue:(SKPaymentQueue *)queue updatedTransactions:(NSArray *)transactions { 
        for (SKPaymentTransaction *transaction in transactions) {

        //debug - finish all transactions to make queue empty  
        [[SKPaymentQueue defaultQueue] finishTransaction:transaction]; 
/*
            switch (transaction.transactionState) {
                case SKPaymentTransactionStatePurchased:
                     //your code 
                     [[SKPaymentQueue defaultQueue] finishTransaction:transaction];
                     break;

                case SKPaymentTransactionStateFailed:
                    //your code 
                    [[SKPaymentQueue defaultQueue] finishTransaction:transaction];
                    break;
            }
*/
        }
    }

then after replace it back by your code and try to make purchase.