I am running Magento 2.2.7 and paypal flow pro to run all CC and paypal payments. Out of the blue ONLY manually entered Credit Cards fail on the FRONTEND. But using stored credit cards works. Other payment methods also work. Such as Affirm, Amazon, PayPal Account payments, PayPal Credit & PayPal Express
Backend CC charges manually entering the numbers works without a problem.
Error in Console =
/paypal/transparent/response/:1 Failed to load resource: the server responded with a status of 500 (Internal Server Error)
Things I have tried
1) Just about every single option found on the web.
2) Updating shopping Cart we are using Firecheckout to the newest version
3) Magento Core Checkout.