Checkout process gets stuck on Credit Card

[duncan12]

Virtuemart gets stuck on the credit card step of the checkout process. I enter the CC# etc, hit save, then the page refreshes and the CC info is gone. There is no way to buy anything on my site at this point.

I turned on debug and it did not throw any errors. I have my shopping cart set with One Page Checkout disabled. NOTE: when I turn "one page checkout" back on, it WORKS!

I am on VM 3.0.12 and Joomla 3.4.7. I've tried it on the Beez template... same problem. My payment method is Authorize.net. I am using AvaTax. My site is bevaradesign.com. I've left the one page checkout enabled until I can get this resolved.