I kept having an issue with the PayPal Pro Gateway for card type being declined for Mastercard until I discovered that the cbsubs_gateway_accounts table record is being setup incorrectly as follows:
The original issue was in the XML file of the setup.
#5352
Fixed for next nightly (people with issue will need to upgrade and have to check the PaypalPro setting to checkmark MasterCard again and save the Paypal Pro setting)