Audio Dropping or Garbled

Hello - I'm having an issue that is completely baffling me.  I have been editing a large (8 hours) video and breaking it into clips/modules with Pro 20.  I export to Media Encoder 20 and on some of the videos the audio is dropped completely or the audio is very slow and garbled.  If I take the same clip, same encode settings and export from Pro, it's completely fine.

Any ideas?