I took a look at the site and I can see an extra (null) character is being prepended to the location data, which seems to cause the error.
I’m not sure if this is an error with the plugin, or something else. Can you think of any recent recent changes to the system – i.e., new plugins, new PHP version, etc. that might be related?
Here’s an easy way to check if AJAX is working at all on your site. Go to this URL in your browser. If it returns ‘0’ it’s working (replace ‘www.yoursite.com’ with your site)
If you’d like to troubleshoot further here’s the steps:
1. Deactivate ALL other plugins
2. Switch to a standard theme
3. Email me a login (using the contact form)
Probably best to do this on a test site, or make a database copy of the main site to test with.