Paypal Express - Denied Card Sent To - Doexpresscheckoutpayment

So... was working with a customer that was trying to checkout, when they submitted the order via the PP Express Checkout it redirected...with no errors or notices to After investigation it was found the card was being denied. So I went to PP and opened a ticked after a few phone conversations.

This is what I sent:

When a customer attempts to process a credit card via Express and it fails they are redirected to with no error stating what has happened. It should redirect back to our cart with an error.

We use CS-Cart on the front end.

Here is the log from that particular transaction. See the last line.

Requests (http/https request)
Response: TOKEN=EC%2d1C973733AT7039800&SUCCESSPAGEREDIRECTREQUESTED=false&TIMESTAMP=2018%2d06%2d01T20%3a51%3a30Z&CORRELATIONID=1d2daeda490a4&ACK=Failure&VERSION=106&BUILD=46549960&L_ERRORCODE0=10486&L_SHORTMESSAGE0=This%20transaction%20couldn%27t%20be%20completed%2e&L_LONGMESSAGE0=This%20transaction%20couldn%27t%20be%20completed%2e%20Please%20redirect%20your%20customer%20to%20PayPal%2e&L_SEVERITYCODE0=Error

...and PP's response

Thank you for contacting PayPal Merchant Technical Support. I apologize for any frustration caused, but I'll be happy to help out with this.
When you call DoExpressCheckoutPayment to finalize the payment, the customer will be on your website, and if there is an error (such as the one that was presented to you - 10486), then you can either manually redirect your client back to PayPal to choose a different funding source, or you can provide a link for them to click on. The result of DoExpressCheckoutPayment will not redirect the buyer to - it's just an API operation that finalizes transaction details. Keep in mind your eCommerce platform may have already built out the functionality to automatically redirect the buyer back to PayPal upon receiving 10486, the point is, PayPal does not initiate the redirect.
There error you received here, 10486, means that there was a problem with the buyer's selected funding source when you attempted to settle the transaction, and the buyer will need to choose a new funding source to complete the payment. This is why the response message says "This transaction couldn't be completed. Please redirect your customer to PayPal".
For more information about 10486, and how to recover from it, please take a look at our developer documentation here:
Please let me know if you have further questions or if the issue has been resolved so I can close your support ticket appropriately.
I want them to receive an error that the card was declined and sent back to their cart accordingly.
What am I missing here?

Basically it seems the DoExpressCheckoutPayment call works fine for successful payments but not denied payments.

Nothing? Still having this issue.