@mandsconsulting
I was having the same issue as the original poster. However, I have never tried your plugin with any version of WordPress besides 4.4.
After much testing I have narrowed the issue down to a conflict with MailChimp for WordPress.
https://www.ads-software.com/plugins/mailchimp-for-wp/
It seems that your plugin does not like when the Contact Form 7 fields (first-name, last-name) are replaced with the ones MailChimp for WordPress uses (mc4wp-FNAME, mc4wp-LNAME).
