As part of a Microsoft Teams service update that was completed in mid‑January 2026, Microsoft introduced a new Shared tab in Teams channels, replacing the earlier Files tab. This change modified how SharePoint document libraries are surfaced within Teams, particularly for Shared Channels. Following this update, Teams now uses a system‑managed Shared tab to display the channel’s primary SharePoint document library. As a result, document library tabs that were previously added programmatically during the migration are no longer rendered in the Teams client UI, even though:

The tabs still exist at the Microsoft Graph level The SharePoint document libraries remain fully available and intact No data or permissions have been impacted

This behavior is expected and aligns with Microsoft’s updated Teams design. No content has been removed, and all documents can continue to be accessed directly via the Shared tab or through the associated SharePoint site.

Please note that re‑adding the document library tabs via script will succeed at the backend level, but they will still not appear in the Teams interface due to this product change.

Workarounds (limitations apply):

Direct users to the SharePoint site URL Add non‑file app tabs (e.g., links, custom apps), but not additional document libraries Re‑adding the document library tabs via script will succeed at Graph level but will still not render in the Teams UI after this update.