How query breaks Special Considerations for Query Notifications

I have this SQL for my query notification.

SELECT ID, ActivityID, EventID, LocationID, VehicleID, DriverID, PassengerID, TimeStamp FROM dbo.GuestActivities
WHERE Processed = 0 AND DATEDIFF(day,TimeStamp,GETUTCDATE()) = 0

The date test seems to break the Special Considerations but I can't identify what rule it violates. I have all of the prescribed 'SET OPTIONS' on my database. Without the date test the query notification works correctly, I just get more records than I want.

Chris.