An engineer has configured 802 1x for the network and all but one of the APs are passing authentication. Which configuration is causing the failure?

When an AP has 'override global credentials checked,' it means it uses its own distinct authentication settings instead of the centrally managed ones. If these unique local credentials do not match what the RADIUS server, such as Cisco ISE, expects for that specific AP, then only this AP will fail 802.1X authentication while others using the correct global credentials continue to function.

Incorrect switch AAA credentials would typically affect all APs connected to or authenticating through that switch, not just a single AP.

If the controller's 802.1X supplicant credentials were incorrect, it would prevent all APs managed by that controller from authenticating to the network.

EAP-FAST is a legitimate authentication method; merely configuring it on ISE for an AP would not cause a failure unless there was a mismatch in the EAP-FAST configuration itself.