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?

You should find your answer here https://forum.unity.com/threads/audio-mixer-in-addressable-assets.1010263/