I was having the same issue with some, but not all, CAC enabled sites. I tried the terminal command and was able to log in once. Now I'm getting a slightly different error: "The operation couldn't be completed. (POSIX error -9802 - Unknown Error: -9802)".
I also notice that when I look in the Centrify Express window under status, it says: "Authentication attempts remaining: 3." The status never changes even when I have successfully logged into a CAC enabled website.