You likely haven't interacted with Hinata on the couch will all the option. the book only appears in the shop after MC acknowledges/says to the camera they have a need to learn massage.
You have likely skipped one of the options and not realized you have never clicked it (Hinata on couch.) Go back and try them all. Boruto will announce that he needs to learn massage, go buy it from the shop and read it in his bedroom.
