Is it? I took that part of the flow from one of your posts actually. You have set to delete flow.counter.
In the documentation I understand it to be delete msg.counter and made the change as I could not find a reference to delete flow.counter on the "working with context page".
Should I change that back to delete flow.counter?
https://nodered.org/docs/user-guide/context#using-context-in-a-flow