On our CI/CD build system after updating to Jenkins 2.201 this morning the durable-task plugin was updated to 1.31. After update any attempt to use a shell command within a script block in a pipeline on a swarm agent produced a timeout and eventually "process apparently never started" as an error message.
Deletion of the plugin and a forced install of 1.30 resolved the issue
What architecture is your client running on? If it's not Linux or MacOS running on amd64 or i386, then the problem lies in the newly added golang binary durable_task_monitor.
If that's the case, this issue is related to JENKINS-59907.