Contextless Outlook task pane add-in no longer remains pinned in new Outlook, OWA

[ottD]

After a recent Outlook upgrade, contextless Outlook task pane add-ins no longer remain pinned in read mode when changing email selection in new Outlook, OWA.

Your Environment

• Platform: New Outlook on PC desktop, Outlook on the web
• Host: Outlook
• Office version number: Outlook Version 1.2024.1115.300 (Production). Client Version is 20241115003.24. WebView2 Version is 131.0.2903.63.
• Operating System: Window Version 23H2 (OS Build 22631.4169)
• Browser: Chrome

Expected behavior

Contextless Outlook task-pane add-ins, i.e. add-ins with SupportsNoItemContext configured in the manifest are expected to support pinning according to the following documentation: https://learn.microsoft.com/en-us/office/dev/add-ins/outlook/contextless?tabs=xmlmanifest#support-for-the-item-multi-select-and-pinnable-task-pane-features

Current behavior

The current behaviour is that a contextless task pane add-in closes when changing email selection in OWA, new Outlook. This used to work as expected but seems to have changed with a recent Outlook upgrade.

Steps to reproduce

1. Run and sideload attached Repro add-in or any other contextless task pane add-in
2. In OWA or new Outlook, select an email and invoke the add-in task pane
3. Select a different email
4. Observe how the contextless task pane add-in gets closed instead of remaining open

Example add-in

Out-of-the-box Outlook add-in created with yo office and updated XML manifest to include SupportsNoItemContext:
ReproAddin (1).zip

Context

This is significantly affecting the users of our production add-in, as they are forced to reopen it each time they select a new email, reducing the productivity benefits the add-in is meant to provide.

[rkpathak]

Try it by explicitly adding
<SupportsPinning>true</SupportsPinning>

[ottD]

@rkpathak Thanks, I'm aware of the explicit <SupportsPinning> manifest element. However, the documentation (screenshot below) clearly states that no item context in the manifest automatically enables support for pinning without specifying explictly <SupportsPinning> and this used to work until a few days ago. Are you saying that this is no longer supported? If so, can you point me to the updated documentation or the release notes of this breaking change?