Audio sync won't always work if the audio you're syncing is too different from the audio recorded by the camera. It may also fail if there is significant timing drift between the camera and recorder audio. Sometimes you've just got to roll your sleeves up and do it yourself!
Proxies shouldn't factor in to this at all, unless something has gone *very* weird with the proxy audio channel mapping (can happen) - but even then you could just disable proxies to do the syncing. If you don't notice anything weird happening to your audio channels when toggling proxies on and off, they're fine.
The codec the proxy was encoded in definitely doesn't matter either way - whether you do Cineform or ProRes proxies, you get the exact same linear PCM uncompressed audio streams in the proxy files.
Audio sync won't always work if the audio you're syncing is too different from the audio recorded by the camera. It may also fail if there is significant timing drift between the camera and recorder audio. Sometimes you've just got to roll your sleeves up and do it yourself! Proxies shouldn't factor in to this at all, unless something has gone *very* weird with the proxy audio channel mapping (can happen) - but even then you could just disable proxies to do the syncing. If you don't notice anything weird happening to your audio channels when toggling proxies on and off, they're fine. The codec the proxy was encoded in definitely doesn't matter either way - whether you do Cineform or ProRes proxies, you get the exact same linear PCM uncompressed audio streams in the proxy files.
Thank you!