Nothing appearing in lightbox

Hi.

I have Lightbox Plus Colorbox and Contact Form 7 installed but it is not working. When you click on the submit button of the contact form, the lightbox opens with the spinning wheel….but no error message is shown. It’s just blank.

There are no JS errors on the console. The Lightbox Plus Colorbox demo works ok. Any idea what the problem is?

Thanks

https://wordpress.org/plugins/contact-form-7-response-colorbox-popup/