From what I remember the kamasutra is from a special option that unlocks after giving her the normal erotic book and progressing a little bit more into her story (that you get in the normal Scott shop).
I'm not a expert at programming but I think there are probably two ways this error could have happened:
1st: You already gave both the kamasutra and the erotic book to Jennifer before the update however after updating the game it resetted some of the items and since the kamasutra is a one type use item this happened..
2nd: The game thinks that you got the kamasutra earlier than you should be, maybe because it didnt activate the trigger in jenn storyline and then this somehow happened, from what I saw in the walkthrough there's two steps after the first erotic book that you need to do to unlock the kamasutra. The first one is catching her masturbating and the second one is asking her about the book, check if you have done these steps and try maybe doing the optional things like giving her a phone and getting close to Rose.