I have a project file in which there are two audio tracks. For some reason, one of the two tracks - always the same one - will only play with the other enabled.
Another way of putting it is like this: one of the tracks is recorded with a lapel mic; the other with a shotgun. I have two separate sequences for two separate clips. In both sequences, if I link the two tracks and make them a stereo pair, both the lapel track and the shotgun track will play, as long as I play them together.
However, in both sequences, I want to play only the lapel mic. Unfortunately, if I de-link them and make them not a stereo pair, then I get two different results. In one sequence, only the shotgun track will play; in the other, only the lapel mic track. It makes no difference which tracks are on mute and which aren't; it makes no difference if I raise and lower the volume. It makes no difference if I create a brand new project, re-import the footage, and bring it into a new sequence.
The footage was shot full HD and imported pro res HQ. The sequence settings are HD, upper dominance, Pro Res HQ compression, audio 48khz, channel grouped - though it doesn't matter if I make it discrete channels.
Oh, and when I play the single track that I want, I get levels on the level reader - but still no sound. I have checked the mute button and the solo button and they are right.