I have added a widget area to the content area directly in the theme single.php to display this widget in my content pulling the mp3 files from custom fields in the post. It worked fine in the side bar but I wanted it viewed before the comments section on mobile devices so I put it in the content with a widget.
Anyway, this works great on the computer screen and even on my android phone - until - I click on "Veiw Mobile Site" which comes from jetpack mobile option. Then the player doesn't show up.
I don't know if this is a plugin issue or an issue with the idea that I widgetized the single.php file.