Hi, I understand how important it is to get this working smoothly.
The issue usually happens because Outlook isn’t syncing properly with the server, often due to a cached credential or a temporary connection glitch.
Let’s start with a quick check: can you confirm if you’re able to sign in to your Microsoft account on the web?
If that works, try restarting Outlook and clearing the credential cache by signing out and back in.
Also, make sure your internet connection is stable and that any VPN is turned off for now.
If the problem continues, have you noticed any error codes or messages when the sync fails?
That will help us narrow it down.
Regards,
Aron