I have the same problem. To all above suggestions I follows list of my experiences:
– copy AVCHD to HDisk (= no audio)
– rename to .AVI, Premiere CS6 is not supporting file format
– rename to .M2TS (header error)
– rename to .MP4 (= no audio)
– change sequence setup tracks to 5.1 (= no audio)
– the same with AVCHD files from Panasonic HMC151, AC90, Lumix LX7,…
Only successful solution at this moment is converting files to .MP4 with Wondershare Video Converter Ultimate (YES audio is OK, but file size after conversion is about half). I hope should come some good solution from Adobe.