Why do I see every single issue related to this problem as being 'closed' including my unresolved submission recently! This is absolutely infuriating and I saw many posts on this issue. Basically, randomly Traktor decides that it will skip all of your tracks when trying to select the NEXT (+1) track in your library or playlist. There is no logic to this behaviour at all.
I decided to buy Traktor 4 Pro because I thought perhaps this bug would have been fixed but it still remains. Support - can you PLEASE address this issue!