This is installed on a 1.5.5e Zen Cart. The theme is from Template Monster (yes, I know. Not my choice.)

The problem is upon checkout when entering invalid credit card data (Authorize.net (AIM)) there is no error returned to the shopper. The one-page ends up reloading. Using the default checkout the error was appear: http://prntscr.com/t2runn

In trouble shooting, I'm not even seeing the error in the message stack: https://prnt.sc/t2r9ct

The only messages in the console relate to a pinterest error.