We have just updated our site to version Cubecart 5.0.7 as we have problems accepting Maestro / Switch payments. Cubecart can't offer a solution as they said to upgrade to the latest version. Which did nothing, then said to contact Paypal (3D Secure). We contacted Paypal and they replied
The 3D Secure verification doesn't occur from PayPal. It's a separate process that occurs through Cardinal Commerce. If your buyers aren't being prompted to verify their Maestro card you'll need to go through the store software you're using to verify that the 3D Secure process is triggered properly.
If you haven't already I would recommend reaching out to any support or documentation offered by the service you're using to verify that your store is setup correctly.
Thing is we have a Cubecart 4 store which accepts 3D secure payments no problem, so its a problem with Cubecart 5. It could be a basic setting tweak to a php code fix.
The following errors were detected:
Transaction is not compliant due to missing or invalid 3D-secure authentication values