Hi @Darryl
Welcome to our forum!
Is it an entire calendar folder or individual calendar items?
If it is an individual calendar item, you may find the deleted calendar in the deleted items of your Shared Mailbox, however, there is no calendar option that you can move the deleted items to calendar folder in New Outlook. Therefore, it is suggested please switch back to the legacy Outlook (Button in the upper right corner or Help>Go to Classic Outlook) to continue to use the feature.
- Find the deleted calendar>Move to>Choose the Shared Mailbox Calendar>OK.
If it is an entire calendar folder, you may also need to convert to the Classic Outlook and change the entire mailbox to the Folder view by going to More Apps>Folder>find your deleted calendar folder>Move it back to your Shared Mailbox calendar.
- More information: Outlook 365 - restore deleted calendar - Microsoft Q&A
Please kindly understand that many functions are not designed at present. If you have any suggestions or ideas, it's suggested that you could post here. Hope Microsoft will notice this in the future.
Hope it helps!
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