Device_tracker and nmap - api error

Configuration
1

Hi all: I’m having an issue where if I add the following to my configuration.yaml file:

device_tracker:
  - platform: nmap_tracker
    hosts: 192.168.1.1/24
    home_interval: 10

and the following to known_devices.yaml:

jay:
  name: Jay's phone
  mac: XX:XX:XX:XX:XX:XX
  picture: /local/images/Jay.png
  track: yes
  hide_if_away: no

I receive an error on attempted logon that states “Unexpected result from API”. When I remove the device_tracker instance of nmap the error disappears and I can logon successfully. Unfortunately, the home assistant log file is blank…

Would anyone know if there is a way to solve this issue? Or a step to setting up nmap that I missed?

I used the all-in-one installer for home assistant.

Thanks!!