I followed the many different articles outlining how to import SSL certificates into IIS exactly and everything worked great except for the fact that when I navigated away from the Server Certificates window, the certificate would disappear. I could see the certificate in the server’s Personal Certificate Store using MMC (Microsoft Management Console) but it wouldn’t show up in IIS.
My problem was that the certificate that I was trying to import only contained the public key and not the private. For decryption to work correctly, the server obviously needs to have both the public and the private key. To resolve the problem I created the needed PKCS #12 Certificate File following the steps outlined here, and then clicked on the Import link (not the Complete Certificate Request… link) in the Server Certificates window in IIS.
From there simply select the .pfx file, enter the password used when creating the file, and you are good to go.