Thanks for reaching out to Microsoft!
It appears the online meeting URL is coming up empty because the Teams for Business meeting provider (Online Teams Meeting) might not be enabled for the user in Outlook/Outlook Calendar.
If you have already enabled Teams for Business for your tenant, please try using the following API:
POST: https://graph.microsoft.com/v1.0/me/events
POST https://graph.microsoft.com/v1.0/me/events
Prefer
Also, please ensure you have the required permissions "Calendars.ReadWrite"
to create an event.
For more details, refer to this document: Create event
Similar post: - https://learn.microsoft.com/en-us/answers/questions/815263/microsoft-teams-url-is-missed-when-creating-a-even
Hope this helps.
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