Jenkins pipeline job stuck forever

We have a Jenkins master with 2 agents that run our builds.
Recently, while a job was running, our network got screwed up - AND one of the agent VM’s disappeared - permanently.
The job was running on that Agent.
We deleted the agent, and created a new one.

THEN we noticed that the job that had been running on the deleted Agent - thinks it’s still running.
Click on the terminate button, and nothing happens.

The console log of the job shows:

15:21:29 Body did not finish within grace period; terminating with extreme prejudice
17:29:27 Aborted by John Lussmyer
17:29:42 Click here to forcibly terminate running steps

Clicking on the “forcibly terminate” link does nothing.
HOW can we get that build to end, so a new build can be started on the new agent?