Unity Sound not working with Xbox Build

Yes, this was implemented in 2.02.11

You will need to call this function before the FMOD.System is created, which is easiest to achieve by adding a PreSystemCreate implementation to the FMOD Unity GameCore platform:

//Assets/Plugins/FMOD/platforms/gamecore/src/PlatformGameCoreScarlett.cs
namespace FMODUnity
{
     public class PlatformGameCoreScarlett : Platform
     {
...
+        internal override void PreSystemCreate(Action<FMOD.RESULT, string> reportResult)
+        {
+             reportResult(FMOD.GameCore.XMAConfigure(false), "FMOD.GameCore.XMAConfigure");
+        }
...
    }
}