You should see them now!
Please contact Leanpub support at email@example.com if you do not.
It used to be that the features available for a book were set according to the plan of the Primary Author of the book. On July 21, 2022 we changed our policy on co-authors and plans: now if any author (not just the primary author) of a book has a Standard or Pro plan, the book gets the Standard or Pro plan features.
(If more than one author has a plan, the best plan wins, obviously!)