I have replicated this a few times on different workstations and users and wondering if any one else is having this issue
GW Clients 14.2.1 Build 124607 / 1402HR2 Build 123047
Disable "show dialog' in properties of Notify. Notify is running. Open notify and the window pane is 'frozen' - can't clear, delete or do anything with the notifications. Need to exit notify and restart?