I have a problem with the Samsung Calendar app adding unremovable alerts 15 minutes before every externally synced event. Default alerts are disabled in the Calendar app. Google and Samsung calendars (source, not app) are disabled.
My primary calendar is through Outlook, with ~6 calendar sources. Two of those are sync'd from external sources via *.ics. Neither of them have any alert or notification added to the events, either in the original source or in Outlook.
Outlook (the app) syncs locally on the device into Samsung Calendar. From there, Samsung Calendar is adding an alert that cannot be removed to every event. My wife, with same device and similar setup, has the exact same issue.
The only workaround I've found is to completely disable notifications for the entire app, which also disables alerts for the occasional event when I do want an alert. I've cleared data and resynced the entire setup from scratch several times with no change.
From what I can tell, this looks like a bug within the Samsung Calendar app itself. My wife, with same device and similar setup, has the exact same issue. Has anyone else experienced this?