My D100C doorbell chime was previously showing up in my app. Now, there appears to be be no option or setting for chimes, so I cannot even begin to setup the device.

it also is not showing up as a network in my WiFi. 
 

why is this and what can I do? My home hub will not seem to be able to pair with the doorbell as a chime either and I have missed several important visits and deliveries as a result of this problem.