When you play a Soundtrack Pro project, you may hear the audio drop out briefly or hear glitches during playback when the playhead reaches the beginning of a clip in a track.
This can happen if one or more of the track's envelopes has a large number of changes in value just before the clip begins. For example, the image below shows a gradual volume ramp right before the start of a clip.
In this case, you can get the same audible result by placing the desired volume event exactly at the start of the clip, and the clip will play back smoothly. You can Control-click on an automation point and choose either Copy value from previous point or Copy value from next point from the pop-up menu.
Updating to Soundtrack Pro 1.0.2 or later will resolve this.