Hi
Welcome to Centrify community!
May we know what are the recent changes that was performed even since the CAC card stop working?
Also, if possible can you perform an upgrade to our latest 5.5.1 agent to see if that helps on the issue?
If it's still fail, can you help run the following command in terminal:
sctool -D > /tmp/sctool.log
Please send us the /tmp/sctool.log for further investigation. Thank you!
BR,
Ivan