connection to azure IOT is 'stuck'

connection to azure IOT is 'stuck'

I have an Azure IOT connection that has been working for a few months without change.
This morning at 3am (10 hours ago) it stopped.
Azure is telling me that it is receiving no telemetry.
When I visit the thingpark.io/iot-flow console I can see an event showing connection closing about 8 hours ago.

I have tried to do a 'restart' but the status sits on closing and never updates.
I tried to do a deactivate and I get an acknowledgement that it is deactivated the state in the connections overview is still stuck on closing.

The events are not updating so I am suspecting something is wrong at the thingpark iot-flow end.

Any suggestions?