ZAP Firefox Proxy with Smartcard

[kdp]

I'm trying to reach a website that requires Smartcard authentication. I've set up Firefox to proxy to ZAP
(https://www.thedutchhacker.com/configure-owasp-zap-with-firefox/) , however when trying to reach the site when the proxy is set up I get the following:

"An exception occurred while attempting to connect to: XXXX

The exception was: No supported CertificateVerify signature algorithm for RSA key Root cause: SSLException: No supported CertificateVerify signature algorithm for RSA key The following document may be of assistance in resolving this failure: https://www.zaproxy.org/faq/how-to-connect-to-an-https-site-that-reports-a-handshake-failure/"

I have generated a new CA and imported that to the browser. I've also tried with a client certificate configured and activated in ZAP, but have the same result.

If I turn the proxy configuration off (using FoxyProxy), everything works fine. I've tried following the link it suggests to install JCE policy files, but that didn't help.

I did seem to have this working previously, but I can't figure out why it isn't anymore.

Any recommendations on what to check?