I have the same problem when I access my game through mobile browser and have conclude :
1. it seems the loader from C2 will still go to the next layout even though the preload for music not complete, and makes the game unable to play it (I'm already using project properties for preload sounds and preload the sound individually)
2. when I use the conditions 'all preloads complete', it get stuck and not go to the next layout, hinting that the music still not yet ready. I don't know maybe my internet connection was too slow.
3. it needs to refresh the browser multiple times to actually preload all the music until the loader don't appear when we refresh it again. and all sounds will be able to play it correctly.
I want to know how to solve this so the game preload all the sound completely (without getting stuck) before go to the next layout.
sorry for my poor english