I have five Insteon 2852 leak sensors in various bathrooms and basement areas. They all work, in that they send leak detected when tested and manual clear signals, and the batteries currently test good. I monitor battery health with HCA, which sends me an email if the daily heartbeat (ON by Group 4) is missed. But three of the five are failing to send the heartbeat, though they work otherwise. Do some sensors lack this capability, or are these just defective?