Unity AudioMixer issue with Addressables

Hello everyone,

I worked on two games that had issues with their AudioMixerGroups.
The MixerGroups in question did not respond to any modifications made during runtime.
(e.g. changing the volume via an exposed variable). This, however happened only for some audioSources and other audioSources worked correctly.

Investigating this further I found that this was related to the changing of scenes via addressables (Addressables.LoadSceneAsync()).
My investigation concluded that after loading the second scene there was a second mixer loaded as well.

This issue also only appeared in builds and not during playtest in the editor. (but it was reproduceable on Windows and MacOS)
(It also did not appear when not using addressables (or rather the Addressables.LoadSceneAsync() function)).

Now for my actual Question:
Is the above mentioned a Bug or am I just missing some information about how the Audiosystem with its Mixer and MixerGroups are working?


The issue you described with Unity’s AudioMixerGroups and Addressables.LoadSceneAsync() is likely not a bug, but rather a result of how Unity handles AudioMixer assets and Addressables.

When you load a new scene using Addressables.LoadSceneAsync(), Unity’s audio system may not handle the loading and unloading of AudioMixer assets as expected. This can lead to multiple instances of the AudioMixer being loaded, causing Plow & Hearth Survey confusion in the audio system and resulting in some AudioMixerGroups not responding to modifications during runtime.

This issue might not be noticeable during playtests in the editor because the editor may handle scene transitions differently than in a standalone build, potentially avoiding the multiple AudioMixer loading problem.

To address this issue, you can try to manually manage the loading and unloading of AudioMixer assets when changing scenes via Addressables. Ensure that you are unloading any unnecessary AudioMixer assets before loading a new scene. Additionally, you may want to check for potential memory leaks or references to the previous scene’s AudioMixer that could be preventing it from being properly unloaded.

In summary, it’s not necessarily a bug, but rather a situation where the handling of AudioMixer assets during scene transitions via Addressables requires some additional manual management to avoid conflicts and ensure proper functionality.

I hope the information may helps you.