The problematic clip has the voice out of phase, the good one has the voice in phase.
Thank you very much Jim. That was it.
The original video recording was in stereo...but only recorded to one channel. This resulted in the voices to be panned left. So I duplicated the track and switched the channels, then exported the audio to get a stereo track with BOTH channels utilized. This resulted in the voices being panned center, which I thought fixed my issue. Unfortunately this caused a new issue and resulted in the audio being out of phase! (I should have known better!!!)
To correct this I exported the track (just the voices) to a new wav file. Then, when the file was still in the bin, I went to: Clip < Audio Options < Breakout to Mono. This gave me both the right & left channel as separate MONO tracks. I then placed the mono track into the timeline, and removed my out-of-phase stereo track. From the beginning I should have changed the track to MONO rather than my original solution. Oh well...at least I learned something!
I do not know if this was the best way to fix the issue, but it seemed to work for me so I thought I'd share in case anybody else runs into this issue.
Thanks again Jim! I really do appreciate your help.
A simple Fill Left effect would have done the job.