Tracking EAP timing can help to identify issues with 802.1X (i.e. RADIUS authentication) performance. This metric is only available for sensors/SSIDs that are using EAP authentication.
Find the sensor you wish to examine, and click through:
Looking at the WiFi panel, scroll down until you find the AP association time chart:
When you find it, click the + symbol to expand additional content:
The EAP time chart will appear: