Phantom Teams team returning 404 ThreadNotFound, and M365 group with orphaned {Team} flag - support case open 3 months with no resolution

I am the tenant administrator for a small business in France. We have two distinct backend inconsistencies in Microsoft Teams. A support case has been open since 13 June 2026 (case  [Moderator note: Personally Identifiable Information removed]) and neither issue is resolved after three months. I am posting here hoping for either a supported technical answer or a path to a genuine escalation.

Issue 1 - M365 group with an orphaned {Team} provisioning flag

The group was originally created as a Yammer / Viva Engage community (creationOptions: YammerProvisioning, GroupSKU: Yammer). It carries resourceProvisioningOptions = {Team}, but no team exists behind it.

• Get-Team -GroupId -> NotFound in /v1.0/teams/ endpoint
• Get-TeamChannel -GroupId -> NotFound, "No threadId found for TeamId ..."
• Graph GET /groups/{id}/team -> 404 NotFound, "No team found with Group Id ..."
• New-Team -GroupId -> BadRequest, "Cannot migrate Yammer group"
• Teams Admin Center -> the group is listed with an error icon and a Refresh button, showing no channels, no members and no owners, unlike every other team
• Teams client (web/desktop) -> the team does not materialise at all and does not appear in the user's team list

The group itself is healthy: it has members, owners, a mailbox, and its SharePoint site with all our content.

Engineering has concluded that creating a team on this group is not possible because the provisioning history remains attached to the group. I have accepted that answer. What has never been addressed is my alternative request, made on day one: simply clearing the orphaned {Team} flag so the group stops advertising a team that does not exist.

Question: is there any supported way to clear an orphaned resourceProvisioningOptions {Team} value from an M365 group, without deleting the group or its SharePoint site? Deleting the group is not an option, it holds our entire document library.

Issue 2 - Phantom team visible in the client, invisible everywhere else

A team named "test" appears in the Teams client for several users in the tenant. It shows as public, zero members, one default General channel, and cannot be used or removed.

It does not exist in any admin surface: Get-Team, Get-UnifiedGroup (exact, wildcard and -IncludeSoftDeletedGroups), Entra ID active groups, Entra ID deleted groups, Teams Admin Center, SharePoint Admin Center, Graph /me/joinedTeams, and Graph /groups filtered on resourceProvisioningOptions.

A HAR capture of an attempted deletion shows, within eight seconds:

DELETE /api/mt/emea/beta/teams/19:k9xeIcyq-...@thread.tacv2/delete -> 404, errorCode "ThreadNotFound", "Unable to fetch team thread: Failed to execute Skype backend request GetThreadRequest."

PUT /api/chatsvc/fr/v1/users/ME/conversations/19:k9xeIcyq-...@thread.tacv2/properties -> 200 OK

DELETE (same as above) -> 404, same ThreadNotFound

So the same thread ID is rejected by the Teams backend and accepted by the chat service. That rules out a malformed identifier.

Question: how is an orphaned thread like this removed? It is served by the Microsoft backend to multiple users, it is invisible in every admin console, and the client itself gets a 404 when trying to delete it. There is no surface on which a customer or a partner can act.

Evidence already provided to support

HAR traces, Teams diagnostic logs (MSTeams Support Logs and PROD-WebLogs), PowerShell output across eight admin surfaces, Microsoft Graph responses, screenshots including the Teams Admin Center error state, and confirmation that a second user in the tenant sees the phantom team. Support confirmed on 20 July that these were valid and complete.

Why I am posting here

Issue 2 has received no answer at all across several consecutive messages. The most recent request asked me to open the "test" group in Entra ID and inspect its members, owners, dynamic membership, GMM rules, shared resources and app assignments. That group does not exist, which is the entire point of the report.

I have also been advised to engage a Microsoft partner. No partner has access to the Teams backend, and the object is invisible in my own admin tools.

If a moderator or a Microsoft engineer can help route this to someone who can act, or can point me to a supported procedure for either issue, I would be very grateful. I can provide the tenant ID, group ID and full thread ID privately.

Case number:  [Moderator note: Personally Identifiable Information removed]