Could you try endpoint debugging, a new feature in ISE 1.3, and see if that gives a better DEBUG log(s)? You may access it at ISE live log by right-clicking on the endpoint’s MAC address or go to Operations > Troubleshoot > Diagnostic Tools > General Tools > EndPoint Debug.
Also, at exact what point did it give this failure? Right after CWA login and transit to the CPP?
We have configured the outside and inside Interface with official ipv6 adresses, set a default route on outside Interface to our router, we also have definied a rule , which also gets hits, to permit tcp from inside Interface to any6.
In Syslog I also se...