Same problem, this is a C2 issue, I have always used music and recently this has stopped working. I can go back to C2 200 and it works after exporting to xdk and building crosswalk apk. Using 212.2 and 214 I've lost all music.
This is very easy to reproduce and I am surprised this isn't more widespread.
Does anyone have an example of music working in an apk from the latest C2 builds?