Laravel Reverb with Heroku

Has anybody had success setting up Reverb with Heroku?

I've got it all working in my local development environment, but attempting to get it set up in Heroku is a bit of a pain.

• Same codebase deployed to Heroku
• Reverb server starts successfully (logs show: "Starting server on 0.0.0.0:33322")
• But when I trigger a Broadcast, it returns a Pusher error with a 404 not found HTML body

My Procfile:

reverb: php artisan reverb:start --host=0.0.0.0 --port=$PORT

My Heroku env:

REVERB_APP_KEY=[APP KEY]
REVERB_APP_ID=[APP ID]
REVERB_APP_SECRET=[APP SECRET]
REVERB_HOST=[APP NAME].herokuapp.com
REVERB_PORT=443
REVERB_SCHEME=https

Config:

        'reverb' => [
            'driver' => 'reverb',
            'key' => env('REVERB_APP_KEY'),
            'secret' => env('REVERB_APP_SECRET'),
            'app_id' => env('REVERB_APP_ID'),
            'options' => [
                'host' => env('REVERB_HOST'),
                'port' => env('REVERB_PORT', 443),
                'scheme' => env('REVERB_SCHEME', 'https'),
                'useTLS' => env('REVERB_SCHEME', 'https') === 'https',
            ],
        ],

Can anyone point me in the direction of what I need to do to get this working? I'd really appreciate it

Thanks