Running into more and more issues where the end user are authenticating via a smartcard. If the issue is after the initial handshake then we may be able to turn on Fiddler after the authentication and everything is okay. If the issue is specifically to do with the authentication or authentication screens then we are stuck and have no tool to use to debug the issue, especially when it may involve multiple processes.
With appropriate new settings in the Fiddler Options, could the socket connection on a TLS send certificate challenge call the appropriate API to use the SmartCard reader as well as challenge for a pin/biometric instead of reading from a certificate.cer file?