We actually just released a bug fix for the plugin that removes our attempt to smartly grab the URL of the current page the form is on, instead letting the form post to itself. However, I saw your thread here before we released the update, so I was able to instead make that value filterable, while defaulting to the originally intended empty string. If you need help with setting something up for this filter, let me know, as we don’t have any UI item for this.
See below:
/**
* Filters the action value to use for the contact form.
*
* @since 1.1.1
*
* @param string $value Value to put in the form action attribute. Default empty string.
* @param int $form_id ID of the Constant Contact form being rendered.
*/
$form_action = apply_filters( 'constant_contact_front_form_action', '', $form_id );
// Build out our form.
$return .= '<form class="ctct-form" id=' . $rf_id . ' action="' . esc_attr( $form_action ) . '" method="post">';
Let me know if you have any other questions.