Losing audio/video sync in Adobe Premiere with mp4's
Download the 32-bit static build ffmpeg from here and try either of the two methods:

1) regenerate the timestamps

ffmpeg -i input.mp4 -c copy -fflags genpts new-input.mp4


2) Extract audio, import that separately, align starts in timeline and then check

ffmpeg -i input.mp4 -vn -c:a copy input-audio.mp4