Mountain Duck cannot use the certificate in YubiKey when connecting to WebDAV (HTTPS) on macOS.

[ysmzxc]

YubiKey (PIV) Client Certificate Not Usable
I am trying to use a YubiKey (5 NFC, PIV mode) as a client certificate for WebDAV（HTTPS） access. The behavior is as follows:
On Windows
• The certificate on the YubiKey is visible in the system certificate store
• Mountain Duck can successfully select and use it for client authentication
On macOS
• The YubiKey works correctly at the system level (e.g., login and browser authentication both prompt for PIN and succeed)
• However, the certificate does not appear in Mountain Duck’s client certificate list
• It is also not visible in Keychain Access
Additional Testing
• Using OpenSC (pkcs11-tool), I can see both the certificate and private key after login
• I have configured:
pkcs11.provider=/Library/OpenSC/lib/opensc-pkcs11.so
• However, Mountain Duck / Cyberduck does not trigger a PIN prompt and does not appear to load the PKCS#11 provider
Based on this, I suspect this may be related to the difference between macOS SmartCard (CryptoTokenKit) and PKCS#11 handling, and that Mountain Duck may only read certificates from the Keychain.
I would like to ask:

1. Does Mountain Duck on macOS support using client certificates from hardware tokens (such as YubiKey) via PKCS#11?
2. Is there any way to make SmartCard (CryptoTokenKit) certificates visible or usable in Mountain Duck?
3. Are there any recommended configurations for macOS + YubiKey PIV + WebDAV(HTTPS) scenarios?