If this client would be a smartphone it is very usual too see a lof of authentication requests since the smartphone is probably roaming around and is going on and off WiFi (if the smartphone goes to standby it will go off WiFi).
For each roaming action and/or each re-association a full 802.1X authentication will happen unless the client has support for OKC or 802.11r (most smartphones will not).
If you are seeing a RADIUS timeout in CPPM and the client is a smartphone it is possible the alert message would be "Client did not finish EAP transaction". In this case the client has started the 802.1X authentication but did not finish it, this could be due to user roaming through the building.