Microsoft Outlook - Google Sync Issues

Question

I have a Microsoft 365 Individual subscription. I use the New Outlook desktop app on Windows 11 and have my Google account connected for two-way calendar sync. Two days ago, the two-way sync between Google Calendar and Outlook stopped working completely. Events created in Google Calendar do not appear in Outlook, and events created in Outlook do not appear in Google Calendar. Previously, this sync was working perfectly — including two secondary Google calendars called Local Consultancies and Travel Itinerary, which would sync instantly and in real time in both directions. These secondary calendars have now completely stopped syncing. They are visible in Outlook's left panel but show absolutely no events, despite having many events in Google Calendar. Here is everything I have already tried:

• Removed and re-added the Google account in Outlook multiple times
• Cleared Windows Credential Manager
• Cleared Outlook cache Full uninstall and reinstall of Outlook
• Changed my Google account password
• Revoked and re-granted full Google permissions to Microsoft (Gmail, Calendar, Contacts, Drive)
• Tried Classic Outlook (Gmail is IMAP only, no calendar sync)
• Verified Google account security — no unauthorised access

The Google account shows as connected in Outlook with no errors. All permissions are granted on Google side. But new events created in the primary Google Calendar do not sync to Outlook at all, and the two secondary calendars (Local Consultancies, Travel Itinerary) show no events whatsoever despite being listed in Outlook. This appears to be a server-side sync token issue with my account that cannot be fixed from the client side. I need Microsoft to investigate the Google Calendar sync at the backend for my account

Answer 1

The described behavior matches a known class of issues where Google accounts synced to the Microsoft Cloud stop syncing calendar data, including shared/secondary calendars.

From the available information, only the following points are documented and can be relied on:

1. When Google accounts are synced to the Microsoft Cloud for use in Outlook (new Outlook for Windows, Outlook for iOS/Android, new Outlook for Mac), a copy of email, calendar, and contacts is stored in Microsoft data centers and synchronized between Google and Microsoft. This backend sync is what enables two-way calendar functionality for non-Microsoft accounts.
2. Calendars shared in Google Calendar (including secondary calendars) are expected to appear automatically in the left pane in Outlook when using this Microsoft Cloud sync. The “Open Shared Calendar” button does not work for Google calendars because shared calendars are surfaced automatically.
3. There is a documented limit of 20 shared Google calendars that can be surfaced in Outlook. If more than 20 calendars are shared, only up to 20 will be available.
4. Some Google calendar features do not sync or appear in Outlook (for example, attachments in events are not supported, and Google’s “Weather” calendar does not appear). The “Birthdays” calendar appears as “Contacts” in legacy Outlook for Mac.

Given that:

• The Google account shows as connected with no client-side errors.
• The calendars (including secondary ones) still appear in the left pane but show no events.
• Client-side remediation steps (removing/re-adding the account, clearing cache/credentials, reinstalling Outlook) have already been exhausted.

The remaining actions are:

1. Verify that the total number of Google calendars shared with the account does not exceed the 20-calendar limit. If more than 20 calendars are shared, reduce the number of shared calendars in Google Calendar so that the total is 20 or fewer, then allow time for the Microsoft Cloud sync to refresh.
2. Confirm in Google Calendar’s web settings that invitations and events are configured to appear on the calendar (Settings → General → “Automatically add invitations to my calendar” must be set to one of the “Yes” options) so that meeting invitations and events can be responded to and surfaced correctly in Outlook.
3. If the issue persists after confirming the above and waiting for sync to run, this falls into a backend synchronization problem between Google and the Microsoft Cloud service. In that case, the next step is to open a support request with Microsoft 365 support so that the Outlook/Microsoft Cloud backend team can inspect the account-level sync state and tokens for the Google connection. Provide them with:
   • Confirmation that the account is connected in new Outlook and shows no client errors.
   • The fact that primary and secondary Google calendars previously synced bidirectionally and now show no new events.
   • Confirmation that the number of shared calendars is within the 20-calendar limit and that Google Calendar settings for invitations are correctly configured.

Backend investigation is required when the Microsoft Cloud sync pipeline for a specific Google account stops updating despite a healthy client configuration, as client-side actions alone cannot repair server-side sync state.

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References:

• Known issues syncing Google accounts to the Microsoft Cloud
• Sync your account in Outlook to the Microsoft Cloud