How to reproduce:
1. Open the attached “IN-134476_AudioBug” project
2. Open the “SampleScene”
3. Make sure your speakers/headphones are not muted
4. Enter Play mode
5. Listen to audio output

Actual result: No audio can be heard
Expected result: Audio track can be heard

Reproducible with: 6000.0.68f1, 6000.3.9f1, 6000.4.0b9, 6000.5.0a7
Couldn’t test with: 2023.3.0a2 (Audio track does not work on Timeline)

Reproducible on: macOS 26.3 (M1 Pro), Windows 10 (user)
Not reproducible on: No other environments tested

Notes:
- The issue does not reproduce if TimelinePlayable has two or more outputs
- Timeline package version does not affect reproduction