When an agent is taken offline due to insufficient disk space the admin monitor 
MonitorMarkedNodeOffline is activated. But once the problem is fixed and there are no more agents that are taken offline due to disk issues the monitor is still shown.
While one can dismiss this message this is counterproductive as it will just disable the monitor and not reset its state. Renabling it will immediately show an alert again.
 
Suggestions
1. Add a reset button in the alert 
2. When marking a node online again, loop over all nodes to find if there is still an agent offline with an instance of MonitorOfflineCause