Workflow Graph is blank, or missing transition lines

• Go to https://nightly.nuxeo.com/nuxeo/ui/
• Create a workspace, if needed
• Add a file
• Start the Serial Document Review workflow
• Use the breadcrumb to open the workspace
• Open the file you just uploaded
• Click the "Process" button
• Open the workflow graph (it should work)
• Use the breadcrumb to open the workspace
• Open the file you just uploaded
• Click the "Process" button
• Open the workflow graph (it should fail)

Expect: the graph is rendered
Actual: the graph is blank