Host notifications are only sent to the broadcasters chat feed so you’ll have to logged into chat as the broadcaster ie same user as the channel.
There’s been a few reports of it not working correctly. And/or doesn’t fire when the viewer count is low. So best to retest and log all the raw lines that Chat sends
The msg-id docs are a little odd as they cover a large number of possible message ID’s but not all of them are active/in use it’s more of a glossary.