Audio issues with TimelineAsset to Playable

I'm creating a PlayableGraph and connecting authored TimelineAssets. I use TimelineAsset.CreatePlayable.
If I set that playable to the source of the AudioPlayableOutput, it works fine. So like this;


But, I want to have an AudioMixer with multiple Timelines input to it. If I add an audio mixer and one or more playables created from the Timeline asset, everything says it's playing, but I hear no audio.
Like these two examples, the last is what is my goal (I think);





I've tried stripping the Timeline node from the playable that is generated from the TimelineAsset. That actually works. Audio plays, but I get spammed with FMOD errors.

Am I going about this wrong?

using Unity 2020.3.14f1