How to reproduce:

1. Open the attached project and the only scene in it.
2. From the Terminal navigate to the AB folder where asset bundles are built.
3. Start local host for the asset bundles with "python -m SimpleHTTPServer" command.
4. In the Editor play the scene and notice audio sometimes is not played.

Expected behavior: Audio retrieved from an asset bundle always played as expected.
Actual behavior: Audio retrieved from an asset bundle sometimes not played if Resources.UnloadUnusedAssets() is called.

Reproducible: 5.5.0a5, 5.4.0f3, 5.3.6p1, 5.3.5p6
Not reproducible: 5.3.5p5, 5.3.5f1