Jenkins intermittently enters a state where:

1. Any started pipeline jobs hang indefinitely on sh, bat, and sleep steps regardless of if they are executed on master or an agent, Unix or Windows systems
2. Pipelines without sh/bat/sleep steps complete, but do not release their executors when completed
3. Using "/stop" on the pipeline job is completely unresponsive, but "/term" and "/kill" works
4. Jenkins is otherwise responsive
5. *Update* Executing shell/batch commands with groovy using String.execute() does NOT hang, but at the end of the pipeline, the executor is still not released.

The following Pipeline script with "sleep"

node('NodeName') {
  echo 'Hello World'
  sleep(1)
}

results in hanging at the sleep step... 

[Pipeline] node
Running on NodeName in C:\Jenkins_work\workspace\test_sleep_hang
[Pipeline] {
[Pipeline] echo
Hello World
[Pipeline] sleep
Sleeping for 1 sec

This pipeline script completes, 

node('NodeName') {
  echo 'Hello World'
}

but does not release the executor on "NodeName" and then other jobs are blocked from running on that node as executors are exhausted.

*Update* Multiple ThreadDumps attached from described Jenkins state.