I have found a plethora of other forum posts (from ~2013) on this subject and not a single one has solved this problem. I am running 22.214.171.124 with AJAX checkout (they say it's a payment method error). Other payment methods (bank transfer) will redirect to our success page but NOT Paypal Pro (which is integrated into the checkout).
I'm at a loss and completely burned out on this. Any help would be greatly appreciated.