The queue api is missing essential data in a workflow job.
In item _class "hudson.model.Queue$BuildableItem" with a task_class hudson.model.FreeStyleProject there are (amongst others) 2 actions classes hudson.model.ParametersAction and hudson.model.CauseAction. these action classes are missing at task class with value: org.jenkinsci.plugins.workflow.support.steps.ExecutorStepExecution$PlaceholderTask.
This was discovered while debugging the Jenkins plugin: https://plugins.jenkins.io/stash-pullrequest-builder which needs this data to abort builds. The classes are added when the builds are created but not available in the queue (api). These classes are however available in a Job build api. See attached XML-file for example.