I know this question is old but I'll answer it in case anyone else has problems.
Try power cycling your modem, also check your RSSI or Received Signal Strength Indicator (a measurement of the signal strength received from your WiFi Router at the Doorbell), it should not be higher than -69.
To get to see the RSSI from the Dashboard tap on the gear on the top right of the doorbell screenshot. You will get to a menu with tiles at the bottom. Tap on the Device Health tile and make sure the RSSI is below -69 to make sure you have a good WiFi signal to your Doorbell.
If that doesn't work make sure to use the motion wizard by tapping on the motion settings tile and then the wand on the top right hand side of the motion settings. Choose I'm missing events I want to see and that should get you going in the right direction.