Sharing Calendars via Delegation on Mac not working with Normal Shared Calendar

Copper Contributor

Allow me to begin by introducing my self.  I am an IT Admin for a company that uses all Mac and iOS devices with O365 services.  We choose not to use Outlook and instead use the built in apps on both Mac and iOS for Mail, Contacts, and Calendar.  


Our issue stems from sharing calendars with users in the organization.  To do this we have a common user which we will call *** Email address is removed for privacy ***.  GH user's root calendar is called "calendar" and has the following permissions which allow it to be seen by the Mac's Calendar app as a delegate.  




Here is what the Mac can see as a delegate.  




The GH user now shares a calendar with users or groups (mail-enabled security style) with varying permissions.  As soon as those sharing and permission options are created, as expected the system sends an email with an invitation to the target user to join the shared calendar.  Clicking this link propagates the new shared calendar correctly into iOS and on the Web Portal.  


The now shared calendar also now shows up automatically on the Mac here shown as a calendar called "Fry".  




Now the problem:  When a user creates an event on the Mac under that shared calendar Fry, the event correctly pushes to all other users that can see that shared calendar on Web Portal, iOS, and Mac devices.  However, the iOS devices and WebPortal of the user who created the new event WILL NOT see the event they just created.  If the user has other Macs that are set up with the same delegate set up, they WILL see the event.  Lastly, if the user creates the event on either the Web Portal or an iOS device, the event DOES show up correctly on everyone else's calendar including the same users Mac.  


For some reason, when an a calendar event for a delegated shared calendar is created on the Mac it WILL NOT push to normal shared calendars on either the web portal or iOS devices for that same user.  It will however show up on all other devices of other users regardless if they are Web, iOS, or Mac.  Something is buggy about this and I suspect it's not related to the Mac client but rather how O365 is handling the event of a delegate calendar vs a normal shared calendar.  


I have tested this across three O365 domains with the same result.  I have also tried other Mac calendar apps such as Fantastical.  I am running the latest version of Mojave and can confirm that the issue persists into Catalina.  


Lastly, I know running Outlook will fix the issue since it doesn't rely on delegation to share calendars.  However that is not an option for my organization.  Please help!  This is a big road block for us as users are complaining that events they area creating on shared calendars are not syncing to their other devices yet everyone else can see them. Thank you!  


Calling attention to @Julia Foran  

2 Replies
Hi there,

Apologies for slow response; I was on a long summer vacation and am still wading through emails that came in while I was gone.

I agree that there is likely an issue with the native Mac calendar app, as my understanding is that the issue only happens when the user creates an event from that iCal app. If the user creates the event from another app (iOS native app or an Outlook app), the changes sync correctly. I'm not sure how to debug further other than to report the issue directly to Apple. I believe the iCal app uses the EWS API, whereas Apple's iOS calendar app uses EAS so that would explain the difference between the two Apple apps.

I am curious why your company doesn't use Outlook Mac client though -- feel free to private message me! I strongly support using Outlook as it's definitely the superior experience :)
I have exactly this issue. Frustrating. As you suggest, likely an Apple bug