Synced audio is missing

I have a project in FCP X (latest update) where all my clips are synced clips containing three audio sources. So for any given clip, I have…

Video
Audio from camera
Audio from shotgun mic
Audio from handheld recorder

All of those sources were synced into one clip using the "Synchronize Clips" command. I edited the picture with the default audio from the camera turned on, but now I'm ready to do a sound mix. When I went back through the project today to start switching to the external audio sources, I discovered that although I can see all three audio sources when I open a synced clip in the timeline, FCP only shows the camera mic and one other source in the Channel Configuration in the inspector. It also only shows two sources when I do "Expand Audio Components" on the clips in my project.

Am I missing something? Ideally, I'd like to see all three sources in the Inspector so I can use any source I want. Is there a way to do this?