[FMOD Unity iOS] No Sound After App Resume or Ad — Even After Upgrading to 2.02.28

Unity
,
1

Hey all, I’m posting this to share an ongoing iOS audio issue with FMOD in Unity that’s still unresolved even after upgrading to the latest FMOD version (as of writing).

:bullseye: The Core Issue

On iOS, audio completely stops working after:

  • the app is minimized/backgrounded,
  • returning from an ad (especially rewarded/interstitial ads),
  • or any interruption like phone calls or multitasking.

Once the app regains focus, FMOD doesn’t resume audio, and nothing plays from that point onward — even though no errors are thrown and everything appears normal in Unity.

:counterclockwise_arrows_button: What I Tried

I originally encountered this issue using FMOD 2.02.05, and after seeing some related bugfixes in changelogs, I upgraded to 2.02.28. Unfortunately, the issue still persists in the new version.

Here’s what I implemented to try and fix it:

  • Manually suspending the FMOD mixer on app background/ad start with RuntimeManager.CoreSystem.mixerSuspend()
  • Resuming it later with RuntimeManager.CoreSystem.mixerResume() after a small delay
  • Tracking mixer state with a bool isMixerSuspended flag to prevent double-calling (which can crash on iOS)
  • Delaying resume logic using a coroutine to give iOS time to recover
private bool isMixerSuspended = false;

private void HandleAppLostFocus()
{
    if (!isMixerSuspended)
    {
        RuntimeManager.CoreSystem.mixerSuspend();
        RuntimeManager.CoreSystem.update();
        isMixerSuspended = true;
    }
}

private void HandleAppGainedFocus()
{
    CoroutineRunner.Instance.WaitForRealTimeDelayAndExecute(() =>
    {
        if (isMixerSuspended)
        {
            RuntimeManager.CoreSystem.mixerResume();
            RuntimeManager.CoreSystem.update();
            isMixerSuspended = false;
        }
    }, 0.2f);
}

However — even with this system in place, FMOD still fails to resume audio after ads or app minimization on iOS. No crashes, but no sound either.

PS:The sound resumes after 10-15 secs