I'm running ISE 2.7 Patch 2 and I understand this is a known bug with several support cases raised against it.
It seems many have the issue via some DUO-related config, but in my case it's for eduroam, however the gist is the same - ISE is failing to understand seemingly valid Proxy-RADIUS config it has within its self.
Does anybody know when a Patch is likely available to resolve the issue? No amount of deleting / recreating the config seems to make any difference.
Cheers,
Richard