What language are you attempting to use?
When Twitch (well Everyone that does Webhooks) sends your Webhook data, it is a request of type POST but the data is in the BODY of the request.
And you should reply with a 200 OK not a 100.
if you are using PHP
$webhook_data = file_get_contents(‘php://input’);
If you are using NodeJS, use bodyParser.json middleware
This sounds odd and more like your handler is doing something unexpected.