Clearly spoke to soon. The problem has returned.
Graph Screen - 5m and 3h shows ‘Loading Data’. Month/Week/24hrs shows data but stops at 1pm on the 24th Nov.
Usage Screen - Completely blank on day view but shows some historical data (week/month)
Same symptoms as before.
Close Glasswire and check service. Service shows as running but unable to stop or restart it with error:
'Windows could not stop the GlassWire Control Service service on local Computer.
Error 1061: The service cannot accept control messages at this time’.
Workaround
Killing GWCtlSrv.exe from task manager stops the service and allows it to manually be restarted.
Reopening GlassWire then works correctly.