You need to create a Unity web request to read a file from an APK. I am finding this works fine for reading a file from the StreamingAssets directory on Android:
// Call with StartCoroutine(PlayFromAPK("filename.wav"))
private IEnumerator PlayFromAPK(string filename)
{
UnityEngine.Networking.UnityWebRequest www = UnityEngine.Networking.UnityWebRequest.Get(Application.streamingAssetsPath + "/" + filename);
yield return www.SendWebRequest();
byte[] loadWebResult = www.downloadHandler.data;
CREATESOUNDEXINFO soundinfo = new CREATESOUNDEXINFO();
soundinfo.cbsize = Marshal.SizeOf(typeof(CREATESOUNDEXINFO));
soundinfo.length = (uint)loadWebResult.Length;
ERRCHECK(FMODUnity.RuntimeManager.CoreSystem.createSound(loadWebResult, MODE.OPENMEMORY, ref soundinfo, out Sound sound));
ERRCHECK(FMODUnity.RuntimeManager.CoreSystem.playSound(sound, new ChannelGroup(), false, out Channel channel));
}
public static void ERRCHECK(FMOD.RESULT result)
{
if (result != FMOD.RESULT.OK)
{
UnityEngine.Debug.Log(result);
}
}
Can you please give that a shot and let me know if you are still having trouble loading the file?