Repro steps in blank project:
- Import some music to test with and create a sound cue with it
- Create a new SoundMix asset
- In level blueprint, play the sound cue, then push the mix and use the mix to override the volume of the Master sound class to 0.
- Play and make sure the audio fades out as expected.
- Create a new GameInstance blueprint and set it in project settings.
- Override the Init event and move the sound mix nodes from the level blueprint
- Play and observe that the sound doesn’t fade out like it did previously
I took a quick peek at the code and it looks like this happens because the audio device is created after the GameInstance is initialized, so attempting to use audio functions at that point actually seems to be running them on the editor’s audio device.
If you try to play a sound in GameInstance Init, it seems to not be audible until the game is actually stopped, then runs in the editor with no way to stop it.
I assume this can be solved by initializing the audio device before the GameInstance.
A 0 second delay before using audio functions is also a quick workaround.