I have used (successfully) the multicam edit in FCPX before with a 2 1/2 hour, 4 cam concert with no issues.
But now, I'm editing a music video, which was a one cam shoot, but 11 angles/takes with the song playing in the background....which was too low, but loud enough to visually/audibly sync to the master audio, which I did, and then created a new compound clip for each 11 angles. I figured doing so would create a new version (with good audio), and I'd be ready to roll in the multicam sync. But when I go to "create new multicam clip", with all new compound clips, they ALL end up sitting in one long line together in the new multicam sequence that is created. The master audio has it's own track.
I'm not sure if I'm having a preferences issues, or if the compound clips don't play well together in multicam edit setups. Any help would be greatly appreciated. :)
Try choosing "Clips" from the "new mulitcam clip" window in the "Angle Assembly" drop down.
If that doesn't work;
I would assign a unique "Camera Name" or "Camera Angle" to each compound, and then choose the "Angle Assembly" in the "new mulitcam clip" window and choose Camera Name or Angle, whichever one you end up using.