Redactor formattingAdd not working I've used redactor's custom formatting option before, but now I can't get anything to work. Here's what my file currently looks like:

{
    "buttons": [
        "formatting",
        "bold",
        "italic",
        "lists",
        "link"
    ],
    "formatting": ["p","blockquote"],
    "formattingAdd": {
        "h2": {
            "title": "Heading",
            "args": ["h2"]
        },
        "h4": {
            "title": "Subheading",
            "args": ["h4"]
        },
        "caption": {
            "title": "Caption",
            "args": ["p", "class", "caption"]        
        }
    },
    "buttonsAdd": ["sup", "sub"],
    "linkNewTab": true
}


I have the "h2" and "h4" under "formattingAdd" because I wanted them to use custom titles.

The problem is, none of my custom formats are working. The "p" and "blockquote" from "formatting" are working properly, but the other three styles don't do anything. They appear in the list, but don't restyle the text in the editor, or create the elements in the output. 

Is there something in the syntax I'm missing? I'm in Craft 3, with the redactor plugin updated to the latest version.
That syntax looks to be for Redactor 2. The latest versions of the redactor plugin (starting from 2.0) use Redactor 3. The syntax has changed slightly