I’m getting notifications for Outlook calendar items that were set to ‘no alert’. The calendar entries have been updated. But in Outlook they have not changed. Sync issue?

It’s worse than I thought. The Outlook calendar entries with ‘no alert’ have the default alert from Apple (15 mins). The entries with a notification in Outlook now have two alerts. Apple default at 15 mins and Outlook alert at 10 mins. In short, every entry has a new alert at 15 mins.