
I had some problems importing playlists, where some tracks disapeared, and i dont remember if i had any message of error but im almost sure that i got those messages, so i tried and tested every posibilities that i could imagine, and i found that rekordbox do not accept wierd carachters, like pontuation, accents and so on. so check if those tracks that are missing, had non comum characters or symbols or else. Hope it helps.