Portal web form not moving to next step

I'm configuring a Custom Portal with a Dynamics 365 instance. I've got a custom entity that i'm trying to display as a form on my portal. The form has several tabs but when I display it on the portal, I cannot get it to go past page 2. 

I have the Auto Generate Steps based on Tabs checked, but it just reloads page 2 when I hit the Next button. Any thoughts on this?

Thanks!