Hi Andy, Tim, FAH-G and Jelvidge,
We have not heard your update on this issue for couple days, are you still experience the Outlook Connectivity issue? If yes, please try the two articles I provided in the previous post or below, and confirm with us whether this issue can be resolved or not.
How to repair the connection to
your Exchange Online account in Outlook
Fix
Outlook connection problems after Office 365 upgrade
If the issue persists after performing the steps in the given articles, please reply to this forum thread. I'll send a private message to you to collect your tenant information. With this information, we can involve Escalation Engineer team to investigate it further.
Thanks,
Jolin Qiao