Shop is seeing when they have the Send Notification box checked after selecting Link to Post on their product selection or single product, it's not sending a notification. They have to go back after and select post to app in order for it to go through.
Steps to replicate:
  1. create a product selection
  2. Choose "Link to post" from that selection
  3. Confirm Send Notification is checked
  4. Select a post to link to
  5. No notification comes through the app
  6. Go back to product selection and this time select post to app
  7. Confirm send notification is checked
  8. This time notification DOES come through