Please note this is an old forum thread. Information in this post may be out-to-date and/or erroneous.
Every phpdocx version includes new features and improvements. Previously unsupported features may have been added to newer releases, or past issues may have been corrected.
Please check the included sample Core/embedHTML/sample_8.php that illustrates how to add footnotes from HTML Extended. Your code is not using the correct syntax.