O365: Inbox won't refresh in Outlook in the web

We have now had confirmation from Microsoft that this issue is resolved. Thanks for your patience.

Microsoft have informed us that there is an issue with users receiving email in Outlook in the web.

Please see below for an extract from their status page:

User Impact: User inboxes may not show new email until manually refreshing or after changing folders when using Outlook on the web.

More info: Users may notice this issue after signing in to Outlook on the web for approximately 30 minutes from any browser.

As a temporary alternative access method, users can try accessing Outlook on the web using this URL to circumvent impact:

https://outlook.office365.com/mail/

Users may be able to mitigate impact by signing out and signing back in to Outlook on the web.

Current status: We're continuing to gather HTTP Archive (HAR) traces from affected users to help isolate the cause of the problem. Additionally, we've identified that signing out of Outlook on the web and then signing back in will resolve any cache issues and enable the routing change that was previously enabled, which should mitigate impact.

Scope of impact: This issue may affect any users operating Outlook on the web during long-term sessions of 30 or more minutes via https://outlook.office.com.

Root cause: A recent change is unintentionally affecting how connection requests are directed to Outlook on the web.