I still think AFCIs are snake oil so I am not surprised that 40 or 50' of untwisted wire will round off the spikes on an "arc indicator" test pulse. It is one reason why I question the requirement that the "device" type needs to be next to the panel. If the bedroom is the target area, why not have the device as close to that room as possible? They are trying to see an electronic signature that may never make it down the lousy transmission line that Romex makes.
