Member plugin Authorize.net has a possible bug

Regarding this plugin: https://premium.wpmudev.org/project/membership/ - When we selected the Authorize.net gateway It does not work. If you put $0.00 or Free it goes to paypal buttons. If you put a price the button disappears. If you use any other gateway such as 2Checkout it is fine and goes to the proper checkout. Any ideas as I have alot of time this week going back and forth with support trying to find the right person who handles this.