Newly published form does not display; Display & Edit forms do not render

I have a list created from a template of a list on the same site.  When I create a new Nintex form with no changes to the base default layout of any kind and it previews OK, but when published, the default New Item SharePoint form is still displayed.  The Display and Edit forms flash a "processing" message and render as blank pages.  There is no additional javascript -- although it appears Nintex has added some to the custom box to fix some issues w/ PDF

What could be causing this straight out of the box?

Here are the steps I took:

1. Create a new classic form and make no changes to it
2. Save it
3. Preview it - looks OK
4. Publish it
5. Open a "New Item" -- form displayed is the original SharePoint NewForm.aspx
6. Add a new item & save
7. Display the form -- flashes a message and renders blank
8. Edit the form -- flashes a message and renders blank

Any help greatly appreciated.