"Show In-App Purchases" Not Showing In App Store
I was having same problem for my new app - submitted a question to apple support - they replied:


  The In-App Purchases section of your app’s product page will contain
  the top In-App Purchases for the app only after a minimum purchase
  requisite has been reached. If the number of completed In-App
  Purchases doesn’t exceed the minimum threshold, this area will not
  appear.