If clients cannot authenticate and there is no record of the authentication attempt in Aruba ClearPass Access Tracker, two possible problems that could cause this symptom are:
The RADIUS shared secret does not match between the switch and CPPM. This mismatch would prevent the switch and CPPM from successfully communicating, so authentication attempts would fail, and no record would appear in Access Tracker.
CPPM does not have a network device profile defined for the switch's IP address. Without a network device profile, CPPM would not recognize authentication attempts coming from the switch and would not process them, resulting in no logs in Access Tracker.
The other options are incorrect because:
Users logging in with the wrong credentials would still generate an attempt record in Access Tracker.
Clients configured to use a mismatched EAP method would also generate an attempt record in Access Tracker.
Clients not configured to trust the root CA certificate for CPPM's RADIUS/EAP certificate might fail authentication, but the attempt would still be logged in Access Tracker.