For various technical reasons, Z wave is not used for presence sensors. Zigbee Devices already have a check in routine with their coordinator which is easily adapted to this use but there is nothing comparable in Z wave.
There are a lot of things that can affect the reliability of the zigbee sensor. Mesh strength is one. Interference from boosted Wi-Fi is another. At my own house, the zigbee arrival sensor goes crazy every weekday afternoon around 330. I suspect that one of my neighbors has boosted Wi-Fi and a child who gets home from school around that time.
There are a number of strategies that can be done to improve presence detection. You’ll find many of them discussed in the following topic: