I updated this file on your site to fix the issue:
ROOT/templates/ja_resort/html/com_content/article/default.php
Line 34:
//$isExpired = $this->item->publish_down < $currentDate && $this->item->publish_down !== JFactory::getDbo()-getNullDate();
$isExpired = $this->item->publish_down && (strtotime($this->item->publish_down) < strtotime(Factory::getDate())) && $this-item->publish_down != Factory::getDbo()->getNullDate();
