Conflict with Ticketing Plugin

A few weeks ago Event Espresso, the event ticketing plugin we use on our site, began sometimes showing a “Nothing in Queue” error when some customers (as well as myself) tried registering for events. Here’s our site:

On the advice of Event Espresso, I first deactivated all of my plugins, cleared browser cache, and tried again. The error still showed.

Then I switched from Unite to the Default Wordpress theme, cleared browser cache, and the error cleared.

I repeated this theme switch/cache clearing two more times and only when Unite is activated does the error show.

Note that the error is intermittent but persistent. My wife, the business owner, had it on her browser for five days (even after repeatedly clearing cache) but not on her phone. I’ve had it on my phone for the past two days but not on my browser. Customers have reported it as well.

I love the Unite theme and I’d hate to switch from it. Can you please look into this and let me know if there’s anything that can be done to eliminate the conflict? Your help would be very much appreciated.