We have the problem as well. When importing a video, the corresponding audio from the file is imported with an amount of digital silence at the beginning and the whole sound is moved and not in sync. Not only when playing back, but also when the project is stopped you can see that the audio and video aren’t in sync. For example when going to a Frame with a beep marker, you can see, that the audio-beep is several frames/seconds later on the timeline.
The problem appeared for the first time in the last version of N7 that had the new Video engine and is still there in Nuendo 8.2 and 8.3. It worked perfectly with the old video engine.