Why isn't Pusher working on production server?

I'm using Laravel and Vue to build a full-stack web app.
I'm using Pusher for real-time notifications.

The app dispatches events on a local server, but not on the production server.
I used the Pusher console to determine whether events are being received and both local and production apps do receive events.

Local Versions

"php": "^7.2.5",
"laravel/framework": "^7.0",
"pusher/pusher-http-laravel": "4.2.4",
"pusher/pusher-php-server": "~4.0",

Production versions are identical with the exception:

"php": "^7.2.34",

Local server: Built-in HTTP server (laravel dev server)
Production server: LiteSpeed V7.9 Cloudlinux 1.3

Configuration

.env

BROADCAST_DRIVER=pusher

config\broadcasting.php

 'pusher' => [
            'driver' => 'pusher',
            'key' => env('PUSHER_APP_KEY'),
            'secret' => env('PUSHER_APP_SECRET'),
            'app_id' => env('PUSHER_APP_ID'),
            'options' => [
                'cluster' => env('PUSHER_APP_CLUSTER'),
                'useTLS' => true,
                'encrypted' => false,
                'scheme' => 'http',
            ],
        ],