# Timeline Marker callback not working in Build (but works in editor)

**URL:** <https://qa.fmod.com/t/timeline-marker-callback-not-working-in-build-but-works-in-editor/23123>\
**Category:** Unity\
**Tags:** android, unity, csharp\
**Created:** [July 7, 2025, 5:48pm UTC](https://qa.fmod.com/t/timeline-marker-callback-not-working-in-build-but-works-in-editor/23123 "2025-07-07T17:48:47Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![sirmrcl3an](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/sirmrcl3an/32/8772_2.png) [@sirmrcl3an](https://qa.fmod.com/u/sirmrcl3an)\
**Post date:** [July 7, 2025, 5:48pm UTC](https://qa.fmod.com/t/timeline-marker-callback-not-working-in-build-but-works-in-editor/23123/1 "2025-07-07T17:48:47Z")

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I didn’t see anything when searching about this and hopefully I’m just missing something simple.

I have my banks setup in ‘Assets/StreamingAssets/FMOD/[platform]’

I have a timeline marker callback for everytime a music track loops to do something in Unity. This works great in editor, but when I make a build and test on device (in this case a Quest 3) the timeline markers don’t fire.

One thing I’ve noticed is that when I build, unity copies all my banks to ‘Assets/StreamingAssets/[platform[’ even though my settings show what I noted above. Could this be the cause?

All my audio plays in the build, it’s just that I don’t seem to get any callbacks. Very strange.

Any help is appreciated! Loving the power I will soon have using FMod.

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**Author:** ![sirmrcl3an](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/sirmrcl3an/32/8772_2.png) [@sirmrcl3an](https://qa.fmod.com/u/sirmrcl3an)\
**Post date:** [July 9, 2025, 5:39pm UTC](https://qa.fmod.com/t/timeline-marker-callback-not-working-in-build-but-works-in-editor/23123/2 "2025-07-09T17:39:45Z")

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Ok, I was able to figure this out finally! The handler for the callback was not a static method. REMINDER for everyone using callbacks. They must be static to run on their own thread when compiled out to IL2CPP. I finally found the error buried in the adb logcat. :-/

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**Author:** ![li\_fmod](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/li_fmod/32/6577_2.png) [@li\_fmod](https://qa.fmod.com/u/li_fmod)\
**Post date:** [July 10, 2025, 1:34am UTC](https://qa.fmod.com/t/timeline-marker-callback-not-working-in-build-but-works-in-editor/23123/3 "2025-07-10T01:34:02Z")

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Hi,

Thank you for sharing the information.

Could I please grab a bit more detail to help troubleshoot? Specifically:

- The version number of the FMOD Unity integration you’re using
- A code snippet showing how you’ve set up the timeline marker callback

> [@sirmrcl3an](#):
>
> One thing I’ve noticed is that when I build, unity copies all my banks to ‘Assets/StreamingAssets/[platform[’ even though my settings show what I noted above. Could this be the cause?

It could be, the banks files should reside in the `Assets/StreamingAssets` directory.

During the build process, Unity automatically copies these banks into the appropriate platform-specific subfolder. If your banks are located in `Assets/StreamingAssets/FMOD/[platform]`, Unity might not recognize them correctly during the build, leading to issues like missing callbacks.

We recommend to place your banks directly in `Assets/StreamingAssets` and let Unity handle the platform-specific organization.

Also, have you had a chance to look at this [Timeline callback scripting example](https://www.fmod.com/docs/2.02/unity/examples-timeline-callbacks.html)? It might help verify the setup.

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<div class="post-metadata">

**Author:** ![li\_fmod](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/li_fmod/32/6577_2.png) [@li\_fmod](https://qa.fmod.com/u/li_fmod)\
**Post date:** [July 10, 2025, 1:34am UTC](https://qa.fmod.com/t/timeline-marker-callback-not-working-in-build-but-works-in-editor/23123/4 "2025-07-10T01:34:40Z")

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Thank you for sharing the solution!