Hi @John Schmidt ,
I share an Outlook calendar wife my wife through Microsoft Exchange.
Noticed you've added the tag "Microsoft Exchange Online" as well, so you meant both you and your wife are in the same organization which uses Exchange online, and you shared your calendar with your wife, granting her the edit permission so that she can also create events on the calendar, right?
In order to help narrow down if it's an issue with the Outlook desktop client, please give it a shot by create appointments from Outlook on the web and see if you are able to save the event into the calendar.
If there's no issue in OWA, it's suggested to run Outlook in safe mode from your side. This helps eliminate whether it's caused by any 3rd party add-ins in your Outlook client:
- Exist Outlook.
- Press Windows key + R, type "outlook /safe", press Enter.
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