Symptom
Collection window widened to 30 days. An order delivered on August 4 was newly registered on August 27 and a "delivered" notification went out again.
Cause
The moment you widen the window, closed items become targets again. Only the widening was considered; the back-end filter to drop them was never added.
Fix
★ When you widen a filter, add a matching filter behind it to remove what the widening let in.