I think this problem started when I moved to v2, but I can't remember.
Sound works occasionally and my sound code has not changed.
Here is my relevant code:
B4X:
Sub Globals
Dim sp As SoundPool
Dim introsp,introld As Int
end sub
Sub Activity_Create(FirstTime As Boolean)
introld = sp.Load(File.DirAssets, "intro.mp3")
someothersub
end sub
Sub someothersub
introsp = sp.Play(introld, 1, 1 , 5, 0, 1)
sub
SoundPool may fail on some files and some devices. Make sure that the music file is not too long. You can check the unfiltered logs to see SoundPool error messages.