Second sign-up module won't work

I have just created a second signup module on my wife's site. The first one has been working just fine for more than a year. This second one seems to have all the same settings but when Subscribe is clicked the module colapses to a spinning windmill logo which runs indefinitely. Nothing else happens.

Joomla version is 3.5.1, Joomlamailer version is 2.4.2, I have set up J2Store on the site since installing JoomlaMailer.

This is the URL with the non-functioning subscribe module.
lilianegrace.com/write-your-magnificent-book

The original one on the Home page still works fine. lilianegrace.com/

Thanks in advance for any help.

No suggestions? Can anyone give me a clue as to whether this should be achievable, or why it wouldn't work?

Help! Now neither of my subscribe modules work, just the eternally spinning windmill.

Chrome developer tools shows me this:
XMLHttpRequest cannot load www.themasteryclub.com.au/index.php?opti...ignup&format=raw . No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://lilianegrace.com' is therefore not allowed access.
Does it help?

Hello DerekMelb,

The problem is that for some reason the Joomla function JUri::root() returns "http://lilianegrace.com" but it should actually return the current domain "http://www.themasteryclub.com.au". I can not tell why this happens on your site but most likely it is caused by some 3rd party extension you have installed. You can disable those extensions one by one and see where it starts working. This will tell you what component is causing the problem. You will need to get in touch with the developers of said component as this is the place where it has to be fixed. It's not a Joomlamailer issue.

Best regards,
Pete