[Deann Engvall]

I had to respond to this because I had the same issue and you can just forget all that aggregate stuff. Choose your mic in the OS sound preferences open premiere add a new audio track and make sure it is mono (others are stereo by default) go to preferences and chose system default for hardware. Your mono track will say “ln 1” at the top in the mixer and you can write/record with no problem – found this on Adobe forum. See your microphone is mono. That was the problem all along. Built in microphone splits to stereo so stereo tracks were happy with it.