In my experience Traktor Sync will only work if there is atleast 1 track in the collection prior to syncing, this message tends to only come up when there is nothing for the sync to add to.
It may be a bug but it could also be a limitation of the way Traktor works
@djjatoro Can you please delete this post and make a new thread for this, while the Original post was Traktor related your comment is not relevant to this discussion and should be raised seperately for Christiaan to look into and discuss with you.