XDCAM audio silent in timeline

Hi, everyone... I'm working on my Media Composer with XDCAM footage for the first time. I don't know if that's pertinent, but my problem is that I can only hear the audio from my source clips if I edit them onto tracks A1 and A2 in the timeline. If I try to patch them into A3 or lower, they are not audible. If I drag a clip that I'm able to hear on A1 down to A3, I lose the audio. Now, it looks like I haven't LOST the audio -- the sample plot does show it -- but it just can't be heard on any other track but A1 & A2. Now, anything else -- music, external sound effects, scratch narration -- plays on any track just fine. It's just the source clips. It's just weird. Any thoughts? Thanks to all in advance.