I’ve replicated this twice now. I was frustrated as all can be for a week, but I haven’t had any troubles importing audio since.
It seems that when I imported through file -> import, it wouldn’t take the audio. Then from that point, regardless of how I’d import (mediabrowser or file-import), I wouldn’t get audio.
I ended up reinstalling cs6. And I ONLY used media browser to import my avchd footage (the file structure wasn’t always intact as it should be either), and I’ve had no problem importing.
I decided to test my theory. I opened up a new project, and did import-file. No audio. Same issue happened.
Reinstalled premiere, and only used media browser, and wah-la. I’m tired of reinstalling, so I’m not gonna try and replicate it again, but I hope maybe this can help give some sort of lead.