Homematic JSON Name Resolution not working

I’m struggling to get JSON name resolution working under HASSIO 86.4 running under Ubuntu 18.04. Using xml resolution with the XML-API plugin on the CCU works fine, but once I change to JSON all I get are the serial numbers of the devices. I’m using port 38123 on the Ubuntu server, and I have confirmed that it is open. Here is my configuration.yaml:

homematic:
  local_port: 38123
  interfaces:
    rf:
      host: 192.168.16.13
      port: 2001
      callback_ip: 192.168.16.22
      callback_port: 38123
      resolvenames: json
      username: Guest
      password: *****
    ip:
      host: 192.168.16.13
      port: 2010
      callback_ip: 192.168.16.22
      callback_port: 38123
      resolvenames: json
      username: Guest
      password: *****
    groups:
      host: 192.168.16.13
      port: 9292
      callback_ip: 192.168.16.22
      callback_port: 38123
      resolvenames: json
      username: Guest
      password: *****
      path: /groups
  hosts:
    ccu3:
      host: 192.168.16.13
      username: Guest
      password: *****