Clearpass definitly sends back the correct role which the controller simply ignores since he used machine authentication (I'm guessing that's the "auth type 10" anyway) as can be seen in the debug:
Dec 5 12:48:58 :522044: <INFO> |authmgr| MAC=24:77:03:72:ff:78 Station authenticate(start): method=8021x-Machine, role=logon//, VLAN=300/300/0/0/0, Derivation=0/0, Value Pair=1
Dec 5 12:48:58 :522016: <INFO> |authmgr| MAC=24:77:03:72:ff:78 IP=?? Derived role 'CP-machine' from Aruba VSA
Dec 5 12:48:58 :522049: <INFO> |authmgr| MAC=24:77:03:72:ff:78,IP=0.0.0.0 User role updated, existing Role=logon/none, new Role=role-machine/none, reason=Station Authenticated with auth type: 10
I'll see about disabling the "enforce machine authentiction" on the controller. Guess that should work as it won't realise its a machine authentication anymore.
Thanks for the tip!