PopOver + CF7 = confirmation error after form submission

Hello WPMU support staff,
When I submit details using Contact Form 7 within a popup, I get directed to a page which says: po_onsuccess({"name":"a6f4922f45568161a8cdf4ad2299f6d23-po","delay":1000,"usejs":"no","html":"

The details are being sent through properly, but I'd like to implement a clear confirmation in place of this error page.

CF7 works fine on other pages so I know it has something to do with CF7 + PopOver.