I've brought a Final Cut Pro sound effect into my timeline (motor4.caf). When I skim the sound effect in the timeline it plays properly. But when I play the section where the sound effect is it doesn't playback.
Two things to note: 1) I already have music in the timeline that plays properly. 2) The motor4.caf clip is enabled in the timeline, but it shows up in grey, while the music shows up green. I know the motor4.caf clip is enabled because I can disable it, which turns it from light grey to dark grey; when I enable it again it turns back to light grey.