You probably mistyped as /ban <username> (or if you just want to timeout /timeout <username> <time>) is the correct command as long as you're mod or channel owner in said chat.

did you put the <> in your chat message? ifso thats not gonna work since it looks for usernames and <> are invalid characters for usernames

Close your eyes don't look at chat ??? :thumbupemoj:

you can use the chat commands anytime aslong as you are connected to it

the command should look like this https://gyazo.com/d3067fc6d1e8ef2db3806ba9da331461 (obviously replace GenericUser123 with the user you want to ban)

Please show us what you’re typing. If you’re typing the command as shown then it will work, we need to see what you’re typing to see if there is a typo or something.

You can ban anyone at anytime regardless of whether or not a stream is live as long as you are a mod or the owner of the Twitch channel.

I can't remember whether the moderation shortcuts are an FFZ feature, but those honestly make the process of chat moderation as simple as one could wish for. Two buttons, literally.