High Counselor in YSA Stake cannot see the Calendar

One High Counselor in our YSA Stake cannot view the Stake Calendar. The calendar does not show up in the Stake Calendar list so he cannot check the box to view it. However, his name does shown up in the "Calendar Administrator List" under "Stake High Councilor". The Privacy setting for the calendar is set to "Entire Unit" and its Status is "Active". Also, everyone else can see the calendar.

Have you checked for the calendar under Subscriptions? (Gear icon in the top right > Subscriptions)
If he's not subscribed to the calendar, it won't show up with a checkbox.