Office 365 group calendar missing?

Hi Sajid,

I have found the cause of the problem in my instance so I've place the fix below for you. Please check that this is actually the same problem before using the fix.

In Feb 2018 Microsoft by default HIDE email groups by default. What I found was that the group was there, but actually hidden. There is a way to list the hidden groups and then a way to unhide that group. The SharePoint groups I had that were not hidden were created before Feb 2018, those after wards are hidden from both the calendar and from the address book.

This solution worked for me

#Early 2018 MS stopped Groups from appearing in Outlook calendars or the address book by default
#If a SharePoint sites needs it's original Group Calendar or a Group Calendar is missing from Outlook then you have to unhide that group using Powershell.

#Connect to ExchangeOnline. You will be prompted to log in with your O365 credentials and MFA
Connect-ExchangeOnline -UserPrincipalName xxxxxxxxxxx

# Gets a list of all groups that are hiddenfrom*
Get-UnifiedGroup |ft DisplayName,HiddenFrom*

#Sets a group so that it is not hidden from Outlook or the address book
#Change "Group Name" to the name of the group to unhide
#Unhides the group from SharePoint
Set-UnifiedGroup -Identity "Group Name" -HiddenFromExchangeClientsEnabled:$false
#Unhides the group from the address book
Set-UnifiedGroup -Identity "Group Name" -HiddenFromAddressListsEnabled:$false