Can't check client certs in CherryPy (mTLS)

Question

Is mTLS possible on CherryPy 18.9 / Python 3.12 ?

The server is providing a valid certificate fine and clients are able to validate and connect to it via https without issue.

However, for this particular project, I need to be able to authenticate client certs, so am wondering if it's implemented or a known issue in CherryPy? I have generated client certificates but do not know how to config cherrypy to demand them / make them obligatory - or if its possible?

cherrypy.config.update({
    'server.ssl_certificate_chain': 'ca.cert.pem',
    'server.ssl_verify_client': 'force',
    'server.ssl_verify_depth': 3
})

The above just allows any client in regardless.

Any help or ideas much appreciated :)