MM2.1, Android 5.1.1, Galaxy s6
Today's update has not resolved the issue with audio files not playing when in a book.
When an audio file embedded in a Page resource via (using Media>Browse Repositories>Private files> (select file)>Create alias/shortcut to the file>Select this file), the file is displayed as a URL link on the page. The user may play the file with an external player (not an ideal solution) when tapped.
An audio file in the Book resource (added using the same steps as above) displays as an audio player, yet, no sound is heard when attempting to play. Additionally, if a user clicks on the sound/mute icon, once muted, cannot un-mute.
I can PM access to research the issue.
See attached screen captures.