Using Classic Outlook on Windows for personal email, calendar, and contact management
Hi Azzimonti,
Have you created the appointments in question?
If the answer is no, the issue could be caused by corrupted Outlook data files. To repair the files, please refer to the following article - https://support.office.com/en-us/article/repair-outlook-data-files-pst-and-ost-25663bc3-11ec-4412-86c4-60458afc5253.
If the issue persists, please let me know which Outlook desktop client version do you have - Outlook> File> Office account.
Also, if you are using Exchange online account, please try to delete the appointments from https://outlook.office.com/owa.
Best regards,
Nemanja