I encoded 24p Avid footage in SS to m2v and brought it into Encore. I took the m2v and audio and created a Timeline. The footage and audio line up correctly in the Timeline, but the video is of sync and ahead of the audio by 10 seconds or more. This did not happen with the 1080i footage I imported. Very strange.
Encore does not properly display the pulldown from a 24p m2v, so this is what happens. Your video should play back in sync once burned to disc. If you need to know where to place chapter markers, you should place them according to the audio, not the video.