Last Updated: August, 19, 2026
ISSUE
When viewing a meeting invitation in new Outlook and Outlook on the web, users who received the invite "on behalf of" another person (for example, an assistant managing a manager's calendar via delegate access) would see the meeting's own details correctly, but the calendar preview showing that day's surrounding meetings appeared completely empty.
CAUSE
Shared and delegate calendars in Outlook can be represented internally using one of two data models:
- Legacy sharing model: an older calendar-linking mechanism where the calendar's actual folder reference isn't resolved at initial load time. A separate, on-demand step is required to fetch and attach the real folder reference before that calendar's events can be retrieved.
- Current/hybrid sharing model: a newer mechanism where the folder reference is already resolved as part of the calendar entry itself. The calendar preview feature was not performing that on-demand resolution step for calendars still on the legacy sharing model. As a result, when a delegate opened a meeting for a calendar using the legacy model, the preview's day-view request had no valid folder reference to query, so it returned no events — while the invitation's own details (subject, time, attendees) rendered fine, since those come directly from the meeting invitation itself and don't depend on the calendar folder reference. Whether a given shared/delegate calendar uses the legacy or current model depends on tenant/account-level enablement of the current sharing model, not on anything the end user can configure directly per calendar.
STATUS: RESOLVED
The issues is resolved. Telemetry monitoring confirmed a significant drop in affected sessions starting the day after the fix released, and we've since heard directly from previously affected customers that the issue is no longer occurring.
RESOLUTION
We updated the calendar preview feature to perform the same on-demand folder-reference resolution step that other calendar surfaces in Outlook on the web already performed, so legacy-model calendars are now correctly resolved before the preview attempts to load events. This fix was released to production on August 11, 2026.
Additional information
A small number of cases remain outside the scope of this fix: where a user has been granted delegate/mailbox access to accept meetings on another person's behalf, but has not added that person's calendar to their own calendar list in Outlook. In these cases there is no locally cached calendar entry at all (not merely an unresolved one), so the preview may still not show surrounding meetings. This is a distinct, separate scenario from the one described above, and we're continuing to investigate it.
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See Also
Fixes or workarounds for recent issues in new Outlook for Windows