Embedded mp3 files stored in my Moodle repository were working fine on my site before I upgraded my iPhone to iOS 10. Now they don't play. Although the phone seems to be loading the audio as before when I click to play it (I can see data transmission happening), there is no sound. Disabling HMTL5 audio in Administration> Site administration > Appearance > Media embedding didn't help. The problem seems to be affecting multiple Moodlers. More info and discussion at https://moodle.org/mod/forum/discuss.php?d=340058.

Here's how to see the bug in action. Using iOS 10, go to http://104.154.236.160 (a Moodle site). Log in with user id "bug" and password "tester". Click the green "Go" button to begin the quiz. Click the play button to load the audio. Notice that the audio appears to be loading (the loading-data icon spins at the top of the iPhone screen) but no sound can be heard. Try with iOS 9 and notice that the audio can be heard. You can also see that the audio doesn't work on iOS 10 in the Word of the Day block at the bottom of the Homeroom page.