Does not work add_filter > ava_after_content hook.

Dear Folks and Support Team!

This is my Enfold code:

function misi_pdf_preview()
    {
echo "Hello Word - by content";

}
    add_filter("ava_after_content", "misi_pdf_preview", 10, 0);

I don’t know what happened because… it worked a few months ago… but not today…
Rendering was fine with wp debug, no errors displayed…

So, I had to changed the original Enfold code to the native WP method, this method works:

 function misi_pdf_preview2($content )
    {

         $before = '';
  after = "Hello Word - after the content"; 
  //modify the incoming content 
  content = $before . content . after;

  return $content; 
}
add_filter( 'the_content', 'misi_pdf_preview2' );

Do you have any suggestion to find out why the original Enfold method is not working?

Thanks for your help,
Mihály Földesi