[Plugin: Audio Player] only works on some templates.

The plugin works beautifully here:

https://www.sagestringquartet.com/?page_id=31

but on my default template it only shows up as code:

ie: [audio:trumpet.mp3] is what I see on the page instead of the player.

Header and footer files seem to have the right elements(had to fix the header as recommended in the support page to get it to work at first).

Also, this is not a huge problem, but it appear(on the templates that it works on) I can only add the audio player in visual editing mode. Is there a way to add it with HTML?

Thanks so much for the help.

Best,

Joe