Sierra mail notification sort order

I just upgraded to Sierra from Yosemite and discovered that Mail app notifications do not order correctly in Notification Center. I have Notification Center sort order set to Recents by App, but mail notifications are listed with oldest at top. Notifications for other apps are correctly listed from newest to oldest. Changing sort order to Recents shows the correct order.

How do I get Recents by App sorting to work with Mail? I suspect I have a misconfigured settings file someplace after my OS upgrade....

Thanks,

Joe