FCP X no audio in timeline

I looked at and tried all the previous suggestions about the audio in my FCP X timeline suddenly going silent. Audio works in clips above, but when brought to timeline, I see the waves, but hear no sound. The audio track is black and white. I'm truly stymied. I'm just at the beginning of the project and for awhile the audio worked. I think it stopped when I detached the audio from the video. But reattaching doesn't make the sound come back. I'm already set to stereo and have selected All, have nothing to re-link. Is this an FCP update glitch? I didn't ever have this problem before. How can I get sound back on my timeline?