I had a really hard time figuring out why the Ajax confirmation would not work - no spinners, no message - yet the form did indeed submit, just with no visual indication that it did, but I finally pinpointed it to a problem with the latest version that I updated to.
When the plugin inserts the URL call to the JQuery library, it adds in my domain to the beginning BEFORE the ajax.googleapis.com so JQuery was not being loaded correctly......
I fixed it by manually added a link to the correct URL in my header.php file, but this should go into the "bugfix" requests for the next version.