Document libraries added programmatically as tabs to Shared Channels are not visible

With the recent Teams UX updates, any document libraries added programmatically to Shared Channels no longer appear in the Teams interface even though they do show up when queried through PowerShell.

Following the guidance in https://learn.microsoft.com/en-us/graph/teams-configuring-builtin-tabs%22https://learn.microsoft.com/en-us/graph/teams-configuring-builtin-tabs%22https://learn.microsoft.com/en-us/graph/teams-configuring-builtin-tabs%22https://learn.microsoft.com/en-us/graph/teams-configuring-builtin-tabs%22as well as the approaches I outlined in my blog post https://reshmeeauckloo.com/posts/powershell-teams-add-documentlibrary-as-tab/%22https://reshmeeauckloo.com/posts/powershell-teams-add-documentlibrary-as-tab/%22 using Microsoft Graph or PnP PowerShell, the tabs still fail to surface in the new Teams experience.

The behaviour is inconsistent:

• The same tab‑creation methods work perfectly in standard channels.
• They also work for users who haven’t yet received the new Teams UX.
• And if the document libraries are added manually, they appear as expected in shared channels.

At the moment, I’m trying to determine whether there is a supported way to add document library tabs to shared channels programmatically so that they remain visible in the new Teams interface.

Any insights or confirmed workarounds would be appreciated.