I am experiencing the exact same issue. And we both downloaded the plugin it seems around the same time. Have you possibly released a bad version?
Word for word same problem.
Ajax works for me with everything else (Ninja Form, CF7, etc).
I have blogging disabled as well as wp-oembeds etc. I am currently using Theme My Login to manage my front end users and contact form 7 to accept registration due to a series of requirements with Mailchimp, Registration, Google Spreadsheet Integration, & Referral tracking.
I do have wp-cache enabled in wp-config, and I was using a heartbeat plugin to modify the heartbeat of admin-ajax.php but even with it disabled I have the same problem.
I am deleting the plugin right now.
