Audition Waveform Won't Play

I'm perplexed: My playhead is working/moving perfectly, but I cannot play the waveform circled in Red in the attached image. I can play every other waveform in the image, including the other waveforms in the first Track/Clip.

The waveforms that I have circled in Blue play perfectly when my playhead moves across them. However, when my playhead moves across the waveform that I have highlighted in a Red Circle, it won't play it. It's as though the waveform itself is muted but it is not.

I've checked everything: it is not muted in any way, the other waveforms in track/clip 1 play correctly, there are no effects on that particular waveform. I just don't understand why it won't play that 1 waveform.

As a test, I sent the .sesx file and all accompanying audio files to a friend who opened up the .sesx project, and the problem waveform played perfectly on his computer. And we're both using the latest version of audition.