Sending, receiving, and organizing email in Outlook.com
Has anyone considered the possibility that something changes on Google's end, and not Microsoft's?
Even if this is the case, and to be fair there's a reasonable chance that it is, it would still be on Microsoft to adjust how they are connecting to be in-line with any changes Google made. Unless Google completely shut this type of access down, it'll be on Microsoft to resolve.
If it were on Google's side, would that explain why the Google calendar events still show up on mobile platforms but not desktop or browser versions of Outlook? I have to believe this is somehow tied to the implementations of browser and desktop Outlook.