I'm using a SM-G920V Galaxy S6 with Android version 6.0.1. When I open the calendar app that comes with the phone, tap "More" in the upper right corner and then "Manage Calendars", there's an option to turn "Contact's birthdays" on and off. To me, that would indicate that it has the capability to display your contact's birthdays on the calendar app. However, I've got it set to "On" and only a few of my contact's birthdays are showing up.
Can anyone tell me how to get all my contact's birthdays to show up?