As I mentioned earlier, you can look at the older topic I linked above. In that older post (linking again here), I mentioned that I had to change the audio encoding, and that post linked to a relevant Stack Overflow thread where I learned about specifying the audio codec for the FFmpeg command. That’s what worked for me previously when concatenating video from a Cam OG’s microSD card. I haven’t tried it recently, though, to see if anything has changed (either with the way Cam OG is encoding its streams for the MP4 container or with the way FFmpeg processes the files/streams for creating a new video file).