365 - Delegation and calendar sharing just not working anymore?

[Sheridan]

We seem to have a couple of issues with 365 with things that used to work but no longer do.

 

For example - first issue is a SLT member shares one of their calendars with a group of staff - some see the calendar (but its blank) and some don't even see it at all (in Outlook app and web)

 

So to investigate I assign myself full delegated access to their mailbox (with permission!) so check the sharing - but this doesn't work anymore either. Trying to open any mailbox that I delegate access to just shows the 'Unhandled rejejection: Error: 500:undefined:undefined:undefined' which seems to be permission related. Waiting 24 hours, private browsing, even different PC doesn't rectify this and it fails when I delegate to any mailbox now

 

Both of these used to work fine,  and sharing a calendar isn't a complex procedure so not much to get wrong, but I'm at a loss as to why its not working and also why I can no longer delegate access to check

 

Opened a ticket with MS but a week later I've just had the usual 'try private browsing etc' replies....

[E_G_R2]

Are you using the outlook app or just the web?  We had an issue where users on the old app couldn't see new calendar events on the new app and visa versa.

[Sheridan]

New app and Web. For example one person can see the calendar fine in the new app, and doesn't see the calendar at all in the web version. Another see's nothing in either, and another see's the calendar in both but it shows as empty!

 

All are in the same group - and thats the group that the calendar is shared with (its an AD synced mail enabled security group)

 

The group is quite static and changes rarely so I don't think its a sync issue, and the loss of beign able to delegate to have a look is a real problem as well

[E_G_R2]

Can only say that with ours it was limitation in new outlook on how it handled shared calendars.  Moved staff away from old outlook and it was fine.  If you are saying that everyone is on new outlook then maybe there is a complex permissions thing going on that it can't handle.  

 

We used Co Pilot and Claude to sort it out.

[Sheridan]

We're using a mix of old Outlook, New Outlook, Web Outlook and Outlook iOS app - and users can have a mixture of results. Even when they see the calendar its blank so its a mess. 

[Sheridan]

Even when the calendar is shared directly with the user and they can see it,  its just blank with a warning they can't change the location (it should have all day events in this week)

 

I think calendar sharing is pretty broken for us

[psydii]

mailbox access by group has always been flaky for us on 365/exchange online.  Sometimes it just works. Other times we have to remove and re-add the group each time the membership changes, and other times, only direct access (with each user given a specific ACE) seems to allow it to work.

[Sheridan]

1 hour ago, psydii said:

mailbox access by group has always been flaky for us on 365/exchange online.  Sometimes it just works. Other times we have to remove and re-add the group each time the membership changes, and other times, only direct access (with each user given a specific ACE) seems to allow it to work.

I tested this by adding one user (who's already in the main group) individually and its the same for them - calendar shows up but is empty. Its very variable what they see

[psydii]

What are the time-zone settings for that user? Is there a chance they're shifted by 12hrs so all the events appear 8pm-6am?

[Sheridan]

We're all the same domain/time zone - its very bizarre as they can often see the calendar but its blank!

[Sheridan]

Its definitely a borked option for us, I exported the calendar as a pst, imported it to a test account and then shared it with a specific individual

 

They see an empty calendar. Or nothing depending on which app/web they use. So calendar sharing is useless in 365 as far as I'm concerned as its so unreliable

 

 

[E_G_R2]

If your using 365 its better to use calendars linked to Teams or SharePoint sites, its the new way of working.

 

Don't shoot the messenger, I know how difficult it is to get people to work in teams or Sharepoint when they have been using email and shared calendars. 

 

I still think your problem is the clash between new Outlook and old.

[Sheridan]

Yeah sharepoint is one way, but the whole idea is that they can see the shared calendar next to their own in Outlook (whatever version! 🙂 ) - it used to work a few years back but its obviously not going to be fixed. Logged a ticket with MS a week ago and they're not come back with anything useful. Shame as it was good when it worked

[E_G_R2]

Bit like outlook online, you have to open another tab to see another mailbox that you have access to whereas in Outlook they appear on the same screen.  Staff hate that!

[Sheridan]

Yeah its weirdly inconsistent as well - on my latest test the 'sharee' can see the calendar properly but only in Outlook classic, and even then only with calendar enhancements switched off!

 

Its such a clumsy mess - 365 has become horrible to manage recently and I pine for my GSuite days...

[E_G_R2]

I don't think there is a solution here but this link explains the issue.

 

https://learn.microsoft.com/en-us/answers/questions/4653889/shared-calendars-not-visible-when-switching-to-new?page=2#answers

[Sheridan]

Its daft - outlook classic is the one I care least about! I can't understand why it doesn't work in the web version as thats the most used