Missing "Not Replying to Latest Message" Banner in Outlook PWA Groups

Hello Microsoft 365 Community,

I am experiencing an issue with the Outlook Web App (PWA) when using Microsoft 365 Groups. Specifically, the "You are not replying to the latest message" banner is not appearing when replying to older messages within a conversation thread.

Context:

• We use Outlook PWA exclusively.
• This issue occurs only in Group conversations, not individual inboxes.
• Conversation View is enabled with messages sorted by newest on top.
• ShowNotificationBar is set to True for the affected group mailbox.

Troubleshooting Steps Taken:

1. Checked OWA Settings: Verified Conversation View and Notification Bar settings.
2. Cleared Browser Cache: Performed hard refresh and cleared site data.
3. Tested Across Browsers: Issue persists in Chrome, Edge, and Firefox.
4. PowerShell Configuration:
   • Confirmed with Get-MailboxMessageConfiguration that:
     • ShowNotificationBar = True
     • ShowConversationAsTree = True
5. Service Worker Reset: Unregistered and refreshed Outlook PWA.

Environment Details:

• Outlook PWA (Progressive Web App)
• Microsoft 365 Group Mailbox

Expected Behavior:

When replying to an older message in a conversation thread, Outlook PWA should display a banner like:

"You are not replying to the latest message in this conversation."

Actual Behavior:

The banner never appears, even when replying to messages that are several days old.

Has anyone else encountered this issue or found a workaround?

Thank you for your time and assistance!

Best regards, Noe Chavez AGL Forwarding