Landing page form doesn't work when accessed by Publish Online link

But, the form does work when accessed by ePub and PDF.

I suspect this issue is with the landing page, which my client had another contractor create, and the page is unsecure, FWIW.

But, it just seems odd, that the form works (accepts and sends user info) coming from ePub and PDF, but does not when coming from the Publish Online link.

Any ideas?

I've included links to the PDF and the Publish Online file. The link to the landing page/form in question is on the last page (page 8), click the blue button "Try it out" to get to the landing page with form, then enter info and click submit.

Many thanks

Publish online link:

https://indd.adobe.com/view/9775d50f-917c-477f-9e57-d8e09e43998b

PDF link:
https://www.dropbox.com/s/1m7rv7ijcpzq3r7/GE_MVIQ_Interactive.pdf?dl=0