Here’s what I found on the audio not playing. If it’s an m4a format then:
5. To get WordPress to recognize m4a and m4b files as podcasts, you need to make sure that your web server is configured to serve them with the right content-type. Do this by adding the following directives to your Apache configuration file or .htaccess file:
AddType audio/x-m4a .m4a
AddType audio/x-m4b .m4b