So I have a kitchen sink in my cottage vented with an AAV. That specific line goes right to the cesspool, not connected to anything else except a laundry box which isn’t used. It’s been fine for years and suddenly it started smelling. I unscrewed it, capped it and it took me two weeks to get around to replacing it. During the two weeks it was fine. I just changed it and it smells again. Never seen that before, anyone else run across an AAV that refuses to seal?