RR - AAV’s are a mechanical device and as with all mechanical devices there is the probability of failure (no matter how small). Gases that they are exposed to aren’t necessarily kind to mechanisms (springs). When they fail, and eventually they will, they erase the vent system for that area of the DWV. That is not a good thing as you know.
The next step is how many people test the AAV’s in there house to see if they are functioning properly. Do any of the HI’s in NACHI test the AAV’s they find. I don’t and I used to be a plumber. One of my pet peeves is that plumbers and code inspectors seem to think it is okay to replace a vent stack with an AAV on new construction. Not good.