You can arm Sync by pausing the deck and pressing Sync.
Pressing Sync for the first deck will engage Sync mode for that deck. This deck’s tempo will become the Sync tempo for any further tracks entering Sync mode.
Now press Sync on the track you are introducing to match it to the first track. This will snap the Beatgrids, tempo and the bar position of this track to any other tracks in Sync mode. Beat Sync will maintain this snap even if the track’s Beatgrid changes (i.e. you have manually set a Beat Warp Marker).
Press Sync again to re-sync the track if it has gone out of time.
NOTE: Tracks that sound out of time may have an incorrect Beatgrid or Sync may be disabled for the track.