The workspace management system introduced in JENKINS-2111 is enabled for all projects, not merely multibranch. I had thought this would affect the pseudo-workspaces used by workflow-cps-global-lib, but on closer inspection that seems to not be the issue. Possibly a bug in WorkspaceLocatorImpl. Would need to dig into a reproduction test case. Is /var/jenkins_home/workspace/workspaces.txt not tracking the various branch projects?