Difference bwteen UNTimeIntervalNotificationTrigge

Question

My app is very notification dependent and I have recently noticed some notification issues which never used to be there before iOS 11.2.

1) Calling removeDeliveredNotifications on a notification by a UNCalendarNotificationTrigger does not remove it anymore, but it does remove notifications triggered by a UNTimeIntervalNotificationTrigger. (The fact that removeDeliveredNotifications doesn't work for UNCalendarNotificationTrigger seems very weird)

2) Pressing an action on a notification triggered by a UNCalendarNotificationTrigger results in all of the other notifications triggered with UNCalendarNotificationTrigger's to be removed, but does not remove any UNTimeIntervalNotificationTrigger triggered notifications.

Is this behaviour normal or have I missed something maybe in my Xcode project or in my understanding of these two triggers? Please help...