premiere pro shows a wave form and plays audio for an MP4 file via audio channels preview but will n

I have an MP4 clip on my timeline that PRP shows an audio waveform for.  When I play that clip in the timeline no audio is played.  However, if I right click on the clip, select Audio Channels, select "Left" in the Preview Media Source Channel, and click on the play arrow, the audio for that channel plays properly.  The right channel was never intended to have sound so no surprise it doesn't play.  I've used MP4 clips from this camera with no issues for the last 6 years, with this being the first clip this has ever happened to me on in PRPro.  I've tried using Media Encoder and converting the file to Prores 422 .mxf, and that file also has the same problem.  I opened the file in Audition and the same problem existed, but when I did an Edit/Extract files to mono the new mono audio tracks play fine.  However, when I right clicked on the file in the Files panel in Audition and selected Extract Audio to New File, the extracted stereo file has a waveform, but again there is no audio when I click the play button.   I'm including this in the PRPro forum because that is where I first discovered the problem.