Hi
I am using VP version 4.21 and the clips from my camera are H.246/MPEG-4 AVC. Full HD 1920 x 1080p 60 fps video. These are similar to your AVCHD files.
MPEG4 files will load,play and be can edited in VP. However you need a reasonably powerful system to play and edit them without seeing the video lagging behind the sound which has been my experience. Because of this. I convert all my MPEG4 to MPEG2 and thse edit with no problems.
Try converting your raw files and see if there is any difference.
Nat