paweldebik

I’m experiencing the same problem, or at least something very similar:

clicking on the thumbnail navigates away from the page, and the lightbox window for uploading an image is missing entirely. There’s just the gray background.

For me disabling and enabling the plugin does not work.
What does work is disabling jquery in the backend.

I’d added the following to my functions.php

if (is_admin()){
	wp_deregister_script('jquery');

	wp_register_script('jquery', (get_bloginfo('template_directory') . '/js/jquery-1.7.1.min.js'), false);
	wp_enqueue_script('jquery');
}

The above code works fine, I can now use jQuery in the admin area. But it seems to mess things up for the Just Custom Fields plugin.