Premiere Pro won't render properly, so I've let it render the m4v and aac files then combine them using ffmpeg.
ffmpeg -i "MCU- Supercut P1.24076.65056.m4v" -i "MCU- Supercut P1.24076.65056.aac" -c copy "MCU-Supercut-P1-FINAL.mp4"
This works but the audio desyncs from the video. I assume this is because the video doesn't have a listed length in the metadata, I know the length of the video but I'm not sure how to make ffmpeg follow that.
ffmpeg -i "MCU- Supercut P1.24076.65056.m4v" -c:a acc -i "MCU- Supercut P1.24076.65056.aac" -c copy -map 0:v -map 1:a:0 -disposition:a:0 default -strict -2 -sn -dn -map_metadata -1 -map_chapters -1 -movflags faststart fin_av.mp4