Groups don't appear on new Outlook desktop and web

Dear Minh,

As a forum moderator, I genuinely wish I could inspect the tenant and mailbox state directly to diagnose and fix this for you. Unfortunately, my role here is limited to providing general guidance and steps you can apply from your side.

Since the issue affects only one user while your own account works, and it occurs in both Outlook desktop and Outlook on the web, the evidence points to that user's Exchange Online mailbox, identity, or group-membership state rather than the group itself. You have already confirmed HiddenFromExchangeClientsEnabled is False, so here are some further checks worth running:

1.Verify Exchange sees the user as a member

Check membership directly:

Get-UnifiedGroupLinks -Identity "Group Name" -LinkType Members | 
Where-Object {$_.PrimarySmtpAddress -eq "******@domain.com"} | 
Format-List 
DisplayName,PrimarySmtpAddress,RecipientType,ExternalDirectoryObjectId

If nothing is returned, add the user through Exchange Online PowerShell:

Add-UnifiedGroupLinks 
-LinkType
-Links

Then allow time for membership to propagate before testing again. Removing and immediately re-adding the user can sometimes reproduce the existing synchronization delay rather than resolve it.

For reference: Get-UnifiedGroupLinks (ExchangePowerShell) | Microsoft Learn

2.Confirm the user is internal and mailbox-enabled

Run:

Get-EXOMailbox -Identity "******@domain.com" | 
Format-List 
DisplayName,PrimarySmtpAddress,RecipientTypeDetails,ExternalDirectoryObjectId

Confirm that the affected account is:

• An internal user in the same tenant
• Backed by an active Exchange Online mailbox
• Not represented as a guest or mail user
• Signing in with the same organizational identity that is listed as the group member

Guests and users outside the organization can receive group messages and calendar invitations, but cannot browse or access the Microsoft 365 Group calendar in Outlook or Outlook on the web.

If the user was previously deleted and recreated, compare the user’s current ExternalDirectoryObjectId with the object returned by Get-UnifiedGroupLinks. A stale membership pointing to an older identity with the same email address could explain why the admin center appears correct while Exchange denies access.

For reference: Manage Microsoft 365 Groups calendar - Exchange | Microsoft Learn

3.Test in a clean browser session

Ask the affected user to:

1. Open a private or InPrivate browsing window.
2. Go to https://outlook.office.com.
3. Sign in using only the affected work account.
4. Open People or the Groups section and search for the group.
5. Open the group first, then select its calendar.

This rules out cached sessions involving another Microsoft account or tenant. Since your account works while the affected account fails in Outlook on the web, testing in a clean browser session is more useful than rebuilding the desktop Outlook profile. The group should be opened as a Microsoft 365 Group, not added as an ordinary shared calendar from the directory. Group-calendar access comes through membership, rather than conventional per-user calendar-folder permissions. Microsoft requires the user to be a group member to access resources such as the group calendar.

4.Isolate the scope with a test group

Create a temporary Microsoft 365 Group containing only the affected user and one working user, then test its calendar in Outlook on the web:

Then test its calendar in Outlook on the web.

The result helps isolate the scope:

• If the affected user can access the temporary group calendar, the original group’s membership or mailbox state is likely damaged.
• If the user cannot access any group calendar, investigate the user’s Exchange mailbox, identity, license, or tenant provisioning.
• If both users fail only on the original group, the original group mailbox may require Microsoft support investigation.

5.Check the user’s Exchange license

In the Microsoft 365 admin center, go to Users > Active users, select the user, open Licenses and apps, and confirm a licence containing Exchange Online is assigned and that the Exchange Online service is enabled within it. Also verify the mailbox is not soft-deleted, inactive, or recently restored.

6.Contact Microsoft support

If none of these resolve it, I recommend that the Global Admin in your organization create a service request with Microsoft Support. A technical support engineer can perform a remote session to investigate the situation, verify the backend configurations, and run any necessary synchronization tools to resolve the problem. If the issue requires further attention, they can escalate it to a specialized team for deeper analysis. For detailed instructions on how to get support, please refer to Get support - Microsoft 365 admin. If you don't know who your IT administrator is, please refer to this article: How do I find my Microsoft 365 admin? - Microsoft Support 

For additional assistance, use this link to find the appropriate contact number from your region: Contact Microsoft customer support | Microsoft Support 

I hope this information is helpful. Please follow these steps and let me know how it goes. If you have any questions or need further assistance, please feel free to share them in the comments so I can continue to support you. Thank you for your patience and understanding. I'm looking forward to your reply.

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