Hi @Nivedha Selvam,
To narrow down this issue, please share some more information:
- In OWA do you mean the default calendar is missing? Or it is a calendar manually created by the user or a shared calendar?
- In Teams do you mean the calendar icon is missing? If you run an admin self-help calendar diagnostic in Microsoft 365 admin center, would it return the cause of this issue?
If possible please also post screenshots of the issue symptom so we can better understand the situation.
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