When multicam clips flatten, audio dissapears

Hi!

I've starded to sync some clips to audio using the multicam method. Since I have camera audio, I'm just syncing them by audio. The thing is, when I flatten the clip in timeline, it seems that the camera audio copies itself into the other audio tracks. Here´s some image proof:

-Multicam clip, un-flatten

-Multicam clip opened in timeline, nothing wrong.

-Flattened clip, all audio worng.

Any clue why is this happening?