I am having the same problem on the following site, which is part of a Multisite installation:
https://www.lightreactionmusic.com
(click on Music Player)
At first I was having errors in iOS and in Safari, as in the issues reported here:
https://www.ads-software.com/support/topic/wp-36-audio-player-multisite-accept-ranges-bytes
https://www.technowut.com/2012/05/14/how-to-stream-videos-to-ios-devices-with-multisite-wordpress/
I changed the URLs in the Audio embed shortcode to absolute paths to the files (rather than Multisite redirects) and that fixed the issues in Safari and iOS. It still doesn’t work on a user’s Windows 7 machine running IE10.
Thoughts? Thanks!