Access to SharePoint Online has now been fully restored by Microsoft.
Microsoft have determined that a recently enabled flight change was resulting in impact to user access requests. They have disabled this change and confirmed impact has been remediated.
We will monitor the stability of SharePoint Online for a period of time before updating the status to resolved.
We apologise for the inconvenience this has caused.
Some users may be intermittently unable to access SharePoint Online. Microsoft are currently investigating to identify the issue and establish a fix.