Issue
Group Member is trying to click send subscription button from On-Call Schedule Calendar, but he is not receiving any email notification, other members of the group are receiving the notification.Group members are having "rota_admin" role.
Cause
The group members who are part of Shift tries to click the send subscription button from On-Call Calendar, other than the person who clicked remaining persons were able to receive the email notifications.
Resolution
This is expected behaviour in the OOB (out of box) across all instances.