Task Pane for OWA add-ins doesn't open for shared mailbox

[geoffreyreemer]

When you want to open an add-in in the task pane in a shared mailbox, using the "Apps" icon in the menu bar, the task pane doesn't open. Nothing happens if you click an add-in under "Apps".

Your Environment

• Platform [PC desktop, Mac, iOS, Office on the web]: Office on the web
• Host [Excel, Word, PowerPoint, etc.]: Outlook
• Office version number: n/a
• Operating System: Windows/Mac
• Browser (if using Office on the web): Google Chrome

Expected behavior

For both user mailboxes and shared mailboxes, if you go to "Apps" and click on an add-in, I expect the Task Pane to open loading the add-in. Also, admin deployed add-ins would be visible with icons in the Message toolbar.

Current behavior

• User Mailbox: works as expected behavior
• Shared Mailbox: If I click an add-in under "Apps", task pane isn't opened. "Apps" flyout is just closed again. There are also no console errors/logs. Admin deployed add-ins are not visible separately in the Message toolbar

Steps to reproduce

1. Open a shared mailbox
2. Compose a new message
3. In the Message toolbar, click on the Apps button
4. Click on any add-in icon (tried with a custom add-in and also the "My templates" add-in that's default to OWA)

Link to live example(s)

n/a, reproducible in any shared mailbox

Provide additional details

• We started noticing the issue on Thursday, August 22nd
• Our add-in still works in the background (through Event-based activation)
• If we show an Event-based activation notification with "Open add-in", we can open the task pane that way.
• Noticed a similar issue being reported on August 25th here: https://answers.microsoft.com/en-us/outlook_com/forum/all/my-templates-does-not-open-in-any-shared-mailboxes/611e7f07-6b99-4064-a8e3-cebd80dcf6dd

Context

This issue is affecting customers who try to use our add-in to send sensitive information securely from shared mailboxes.

Useful logs

• [ ] Console errors (n/a, they don't show)
• [x] Screenshots
• [ ] Test file (if only happens on a particular file)

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[kdeshpande-methodcrm]

@geoffreyreemer Did the solution given by @JONTY650413 work for you?

[geoffreyreemer]

@kdeshpande-methodcrm Feel free to try it out first. I'm not downloading a random Mediafire file to solve an issue in a web application, so I'd rather wait for official communication from MSFT instead.

[kdeshpande-methodcrm]

Able to reproduce the same

[andrew-at-acta]

I am experiencing the same issue in OWA.

[rajjha-msft]

Hey @geoffreyreemer

In Outlook on the web, if you open a shared mailbox in a separate browser tab or window using the Open another mailbox option, you may encounter issues when accessing add-ins from the mailbox. We recommend opening the mailbox in the same panel as your primary mailbox instead. This ensures that add-ins work as expected in your shared mailbox.

If you prefer to open the shared mailbox using the Open another mailbox option, we recommend deploying the add-in to both your primary user and shared mailboxes.

For more info, please visit : https://learn.microsoft.com/en-us/office/dev/add-ins/outlook/delegate-access?tabs=web%2Cjsonmanifest

[geoffreyreemer]

I'm not sure if anything changed, but opening add-ins through "Open another mailbox" works again. Problem seems to be solved for us now.