PayPal not accepting credit card payments from Pay Now button

If my customers do not have a PayPal account and wish to pay by credit card they should be able to click “Pay with credit or Visa Debit card” on the PayPal payment page after clicking the green Pay Now button from their invoice. When doing so the resulting page has its fields filled with 0s. If the proper payment information is filled in and the Pay Now button is clicked at the bottom of the PayPal payment page the progress spinner appears and then disappears and nothing else happens. The payment never goes through. See the attached screen shot.

I did some troubleshooting and when the Pay Now button is pressed PayPal is giving a VALIDATION_ERROR. Payments work great if the customer logs in using a PayPal account but some of my customers do not have a PayPal account and wish to pay by credit card using PayPal. Is this a known issue with InvoicePlane? How can I get paying by credit card through PayPal working? It would seem InvoicePlane is sending all 0s for the required fields.

EDIT: I am using the latest InvoicePlane version 1.4.3