Final Cut Pro X 10.0.6: Some Compound Clips may not open in the Timeline
In Final Cut Pro X 10.0.6, some Compound Clips may not open in the Timeline when you double-click them. This can occur if you have Compound Clips in your Project that were created in a prior version of Final Cut Pro X (10.0.5 or earlier).
To open the Compound Clip in the Timeline:
Click the Compound Clip to select it.
Choose Clip > Open in Timeline or Control-click the Compound Clip and choose Open in Timeline from the contextual menu.