The client experienced high load on their CPU. Restarting the K2Service solved the issue temporarily.
We gathered Memory Dumps using the ProcDumpTool.
We analysed the Dump File provided and highlighted 12 threads busy waiting for an object in the HostServer, or all are waiting for a process or a deadlock occurred.
They have identified Authentication Deadlocks with SSO.
This is a known issue that has been subsequently fixed in 4.6.11.