Symptoms

Client event notifications were not being sent.
 

Diagnoses

A check of the hostserver logs revealed the following error:
System.Messaging.MessageQueueException (0x8004005): Access to Message Queuing system is denied.
 

Resolution

Checking the MSMQ paths in the k2hostserver.exe.config showed that both the EventBus and EventBusError queues were hitting the staging server and they should have been using the production server. We made that correction and restarted the K2 service. This fixed the issue.