Mobile iDEAL payments not being captured - paypal

Question

I have been struggling with this issue for some time now. Even created a support ticket at my Devs PayPal portal, but even the devs seem to not know what exactly is going wrong. Therefor, I'm asking it here, hoping someone can help me.
The issue: I have a website where people have to check out using iDEAL. To process these iDEAL payments, I use PayPal. Everything works great on desktop, but for some reason, the payments are not being captured when I use my iPhone to pay. I even checked it on different devices, but the issue remains.
What happens when I use my dekstop to pay: after selecting the desired bank, I get redirected to the payment page of my bank. I scan the QR code, make the payment, and get redirected to my own website where I store everything in the DB / show success message. The money has been taken out of my bank and added to my PayPal account. (the payment has been captured)
What happens when I use my phone to pay: after selecting the desired bank, I get redirected to the App to make the payment. Once done so, I get redirected to a 'Thank you' page from PayPal themselfs. The money has been taken out of my bank account, but NOT added to my PayPal account, instead it gone missing (and probably gets refunded by PayPal). - the payment has NOT been captured.
The above is whenever I'm not using the sandbox. However, I'm in the sandbox, the same thing happens: desktop payments are being captured, mobile payments are NOT being captured.
When I check the API calls in my PayPal Dev dashboard, I can see when I'm paying via mobile that the order has been created, but never captured. But the order is being created and captured when I use my desktop.
Any help would be appreciated.
This is the part of my code
// CREATE GLOBAL VARS
var invoice_id = '<?php echo $db_invoice_id; ?>';
function submit_database(transaction_id, transaction_amount, transaction_status) {
// DEBUG
console.log('---BELOW PAYPAL FUNCTION---');
console.log(invoice_id);
console.log(transaction_id);
console.log(transaction_amount);
console.log(transaction_status);
$.ajax({
type: "POST",
url: "/data/betalingen/herinnering/",
data: {invoice_id: invoice_id, transaction_id: transaction_id, transaction_amount: transaction_amount, transaction_status: transaction_status},
success: function(data,textStatus,jqXHR){ start_processingIDEALPayment(data,textStatus,jqXHR); }
});
function start_processingIDEALPayment(data,textStatus,jqXHR) {
// DEBUG
//alert(data);
console.log(data);
if (data == 'success') {
$('.access-purchase .actions').hide();
$('.access-purchase .content-inner .description').removeClass('alert-danger');
$('.access-purchase .content-inner .description').addClass('alert-success');
$('.access-purchase .content-inner .description').html('<i class="fa-solid fa-check"></i> Wij hebben je betaling succesvol ontvangen. De pagina wordt ieder moment ververst, waarna je toegang zult hebben tot de stream.');
setTimeout(function (){
//Reload page
location.reload();
}, 5000);
}
}
}
paypal.PaymentFields({
fundingSource: paypal.FUNDING.IDEAL,
fields: {
// PREFILL NAME FIELD
name: {
value: "<?pho echo $db_name; ?>",
},
}
})
.render("#ideal-fields");
paypal.Buttons({
fundingSource: paypal.FUNDING.IDEAL,
style: { label: "pay", },
createOrder: (data, actions) => {
return actions.order.create({
"purchase_units": [{
"amount": {
"currency_code": "EUR",
"value": "<?php echo $next_amount_to_pay; ?>",
"breakdown": {
"item_total": {
"currency_code": "EUR",
"value": "<?php echo $next_amount_to_pay; ?>"
}
}
},
"items": [
{
"name": "Betaling voor factuur: #<?php echo $db_invoice_id; ?>",
"unit_amount": {
"currency_code": "EUR",
"value": "<?php echo $next_amount_to_pay; ?>"
},
"quantity": "1"
},
],
}]
});
},
onApprove(data, actions) {
return actions.order.capture().then(function(orderData) {
// DEBUG
console.log('Capture result', orderData, JSON.stringify(orderData, null, 2));
// CREATE VARS
var transaction = orderData.purchase_units[0].payments.captures[0];
var transaction_id = transaction.id;
var transaction_amount = transaction.amount.value;
var transaction_status = transaction.status;
// DEBUG
console.log(transaction_id);
console.log(transaction_amount);
console.log(transaction_status);
// SUBMIT TO DB
submit_database(transaction_id, transaction_amount, transaction_status);
// SHOW MESSAGE TO USER
$('.box.invoice-payment').hide(); // HIDE PAYMENT FORM
$('#openPaymentHandler').hide(); // HIDE PAYMENT FORM
$('#payment-callback').removeClass('alert-danger');
$('#payment-callback').addClass('alert-success');
$('#payment-callback').html('<i class="fa-solid fa-check"></i> Wij hebben je betaling in goede orde ontvangen.');
$('#payment-callback').show();
setTimeout(function (){
//Reload page
location.reload();
}, 3500);
});
},
onCancel(data, actions) {
// CANCELED
//DEBUG
console.log(`Order Canceled - ID: ${data.orderID}`);
var transaction_id = data.orderID;
var transaction_amount = '0.00';
var transaction_status = 'cancelled';
// SUBMIT TO DB
submit_database(transaction_id, transaction_amount, transaction_status);
// SHOW MESSAGE TO USER
$('#payment-callback').removeClass('alert-success');
$('#payment-callback').addClass('alert-danger');
$('#payment-callback').html('<i class="fa-regular fa-circle-xmark"></i> De betaling is afgebroken of mislukt.');
$('#payment-callback').show();
},
onError(err) {
// ERROR
// DEBUG
console.error(err);
if (err == 'Error: Detected popup close') {
var errorMsg = '<i class="fa-regular fa-circle-xmark"></i> De betaling is mislukt, omdat het betaalvenster is afgesloten.';
} else {
var errorMsg = '<i class="fa-regular fa-circle-xmark"></i> De betaling is afgebroken of mislukt.';
}
// SHOW MESSAGE TO USER
$('#payment-callback').removeClass('alert-success');
$('#payment-callback').addClass('alert-danger');
$('#payment-callback').html(errorMsg);
$('#payment-callback').show();
alert(err);
},
}).render("#ideal-btn");