I recorded the sound externally with a double system. The footage was saved on a drive, and was converted to ProRes. I didn’t change the frame rate, left it at 30fps. The external audio slips out of sync by about 1 minute.
I slowed down the audio to approximately 99.94% (depending on the clip), and it stays in sync. The pitch changes by a minuscule amount (almost imperceptible). I can go this route, but eventually I’ll have to convert to 29.97, and I’m not sure what problems slowing down the audio will create when I convert.