In the new version of Outlook, if you're having trouble categorizing appointments or meetings in shared calendars, it's important to ensure that the categorization feature is properly set up. Categories can be assigned to Outlook items, including appointments and meetings, by specifying the names of the appropriate Category objects in the Categories property of those items.
If your shared calendars are not allowing you to categorize items, it could be due to the way the shared calendar is set up or permissions associated with it. Ensure that you have the necessary permissions to categorize items in the shared calendar. Additionally, check if the shared calendar is using the new model of calendar sharing in Outlook for Microsoft 365, as this model supports improved functionality for shared calendars.
If you continue to experience issues, consider reaching out to your IT administrator to verify the settings and permissions for the shared calendars.