Hi!

It sounds like you're encountering an issue with the calendar sync settings in Odoo. Here are a few steps you can take to ensure that all calendar entries are synced as private:

1. Check Odoo Settings: Go to the calendar settings in Odoo and make sure the default visibility is set to private. Sometimes there might be additional options that affect how entries are imported.
2. Review Sync Options: When setting up the sync, check if there are specific options for handling privacy settings. Some integrations have toggles for visibility that might override the default.
3. Permissions: Ensure that the user permissions in Odoo are set correctly. Sometimes, if the user does not have the proper permissions, entries may default to public.
4. Custom Script: If the built-in settings don't solve the issue, you might consider creating a custom script that modifies the visibility of the calendar entries after they are imported.
5. Update Odoo: If possible, check if there are any updates or patches available for Odoo 15 that address this issue.r solutions from users who may have experienced similar issues.

I hope this helps! Let me know if you have any other questions.