Attempt at connecting to OpenMHz websocket

openmhz.py

import socketio
import json
from signal import signal, SIGINT

sio = socketio.Client(logger=True, engineio_logger=True)

@sio.event
def connect():
    print('connection established')

@sio.on('new message')
def my_message(data):
    print('message received: {}'.format(data))

@sio.event
def disconnect():
    print('disconnected from server')

def handler(signal_received, frame):
    # Handle any cleanup here
    print('SIGINT or CTRL-C detected. Exiting gracefully')
    sio.emit('stop')
    sio.disconnect()

if __name__ == '__main__':
    # Tell Python to run the handler() function when SIGINT is recieved
    signal(SIGINT, handler)

    filterSet = {
      "filterCode": "",
      "filterType": "all",
      "filterName": "OpenMHz",
      "filterStarred": False,
      "shortName": "chi_cpd"
    }
    startJson = json.dumps(filterSet)
    print("Sending JSON: {}".format(filterSet))
    sio.connect('https://api.openmhz.com/')
    sio.emit('start', startJson)
    sio.wait()

Output looks like this, no calls are ever received

Sending JSON: {'filterCode': '', 'filterType': 'all', 'filterName': 'OpenMHz', 'filterStarred': False, 'shortName': 'chi_cpd'}
Attempting polling connection to https://api.openmhz.com/socket.io/?transport=polling&EIO=3
Polling connection accepted with {'sid': 'xxxx', 'upgrades': ['websocket'], 'pingInterval': 25000, 'pingTimeout': 5000}
Engine.IO connection established
Received packet MESSAGE data 0
Namespace / is connected
connection established
Attempting WebSocket upgrade to wss://api.openmhz.com/socket.io/?transport=websocket&EIO=3
WebSocket upgrade was successful
Sending packet PING data None
Emitting event "start" [/]
Sending packet MESSAGE data 2["start","{\"filterCode\": \"\", \"filterType\": \"all\", \"filterName\": \"OpenMHz\", \"filterStarred\": false, \"shortName\": \"chi_cpd\"}"]
Received packet PONG data None
Sending packet PING data None
Received packet PONG data None
Sending packet PING data None
Received packet PONG data None