Which Smart card are you using? PIV, Java, .Net or other?
Maybe below works for you:
- Installed corresponding Smart card driver on you Mac and disable PIVToken by below command line from Terminal.app.
- sudo defaults write /Library/Preferences/com.apple.security.smartcard DisabledTokens -array com.apple.CryptoTokenKit.pivtoken
Notes: if you're using macOS 10.13, please make sure quit Keychain app and re-launch Horizon client.
Thanks.