I have noticed that occasionally the dashboard will freeze and some things may get stuck for a while. For example, if I have a dashboard open that shows how many calls are in queue and how many are currently being handled by agents, sometimes a call that an agent is handling will get stuck on the dashboard after the agent ends the call and the dashboard will show that the call is still a live call. Our tech team has explained this to us as a ghost call. After some time (or maybe many screen refreshes) the call will go away like it has just ended.