I was having the same problem. The form used by Job Manager was working correctly but other forms weren’t. Here’s my solution:
– Open the file cf7.php located in /wp-content/plugins/wp-job-manager-contact-listing/includes/forms
– Locate the line: if ( ! array_search( $cf7->id, $this->forms[ $object->post_type ] ) ) { in the function notification_email
– Above that line insert the following line: if (empty($this->forms[ $object->post_type ])) return $components;
The problem is that the function array_search expects an array but the value supplied is null when a form other than the one specified in Contact a Job Form is used.
