Sony A7S III Audio not playing after render

[SWFLfilm]

I used my A7s iii for my first "real" shoot this past week. I used an Azden 300 UPR for the subject and the audio captured was clear and perfect. When I started editing in Premiere and after I exported and .mp4, the client told me they had no audio from the person being interviewed, even though on my MAC I could hear it just fine. They could hear the bumper music and that was about it. When I played the .mp4 on my PC, I had the same issue. After testing a number of different things, I figured out I had to change the audio channels for L+R to both being L. I found that really strange. Is there some sort of work around during shooting I can do so I don't have to take this extra step in post?