Microsoft 365 Groups Email Notifications Delayed in Outlook

I'm experiencing an issue with Microsoft 365 Groups email notifications in Outlook on Windows 10/11. When an email is sent to a M365 Group, it is delivered, and I can open and read it without any issues. However, the problem is with the notification of unread emails.

Specifically, I do not receive a notification next to the group name in the left-hand navigation pane immediately after the email is delivered. If I don't read the email and wait, the unread email count notification eventually appears, but it takes more than 30 minutes for the notification to show up.

There seems to be a noticeable delay between when an email is sent to a group and when the unread email notification is displayed in Outlook. Has anyone else encountered this issue, or is there a known solution?

I am seeing the same behaviour on different M365 Tenants.