I have been trying to figure this one out all morning. My audio keeps disappearing from the timeline. I can see the meters registering it. I can hear it if I use the clip viewer but it's as if the clip is muted or disabled, although it is not dimmed. The checkbox is checked in the inspector.
I have never had this problem, I am suggesting this as you may have "video only" selected for clip insertion. This means you can play clips with audio / video in the event library, and once it is inserted to the timeline you loose audio or video according to the option that was chosen. Did you try it?
so i'm pretty new to final cut pro, i took one class almost ten years ago in college....
i wasn't able to simply drag & drop from the event library. i did have "all" checked for insert, but i was dragging & dropping. once I used the "Open in timeline," to insert the clips, voila! audio heard.... is this weird?