Registrations form only opens once

The following use case is not working in my installation:
1) Open an even registration form by clicking a link in the calendar
2) Press the (x) to close the reg. form
3) Click the same link again.

The result is an empty form that is very narrow in the vertical direction. This code at line 810 in /colorbox/js/jquery.colorbox.js hints at the problem:

// Inserts an empty placeholder where inline content is being pulled from.
// An event is bound to put inline content back when ColorBox closes or loads new content.
$tag(div).hide().insertBefore($(href)[0]).one(event_purge, function () {
$(this).replaceWith($loaded.children());
});
prep($(href));

The content is not being restored to the inline content div. I am looking for advice on how fix this. Also is there a reason why the content needs to be removed from the inline div, is there an easy way to modify this code to copy instead of move?

Thanks for a great plugin.
Jan

https://www.ads-software.com/plugins/event-registration/