Not sure if this is limited to the ZUS products, but the one other Bluetooth device I use works just fine. Both the ZUS charger and ZUS Smart Tire Safety Monitor work fine after pairing, but as soon as I leave the car and come back, they no longer connect. I have to unpair the devices and remove them from the app, restart my phone and repair them. As I often go on short trips, this approach will not work in the long run.
Car: VW GTI (continuous power to cigarette lighter)
Phone: Motorola G5