Blackfriday Lax HTML blocks - is it supposed to be working?

I’ve added the following to my config.toml

extensions = ["laxHtmlBlocks"]

But it doesn’t seem to have any effect whatsoever. Something like

<div>This should be *rendered* as markdown</div>

Will render the text within stars verbatim, contrary to what the extension is supposed to do.

The extension is listed here.