Steps to reproduce:
1. Open the attached project (case_1217337.zip)
2. Under Edit > Project Settings > Player > Resolution and Presentation, ensure that "Run In Background" is unchecked
3. Select "Test" GameObject
4. Open the Timeline Window by going to Window > Sequencing > Timeline
5. Click Play in the Timeline Window itself
6. Unfocus the Editor (By tabbing out, focusing some other application etc.)
Expected result: Audio is paused and is in sync with the rest of the Timeline Tracks when resumed
Actual result: Audio is not paused and continues playing, staying ahead of the rest of the Timeline Tracks
Reproduced in: 2017.4.36f1, Timeline 1.1.0 (2018.4.17f1, 2019.2.21f1), Timeline 1.2.10 (2019.3.1f1), Timeline preview.7 - 1.3.0 (2020.1.0a22)