Steps to reproduce:

1. Edit article_workflow configuration in vendor/ezsystems/ezplatform-workflow/src/bundle/Resources/config/workflows.yml (happens also to custom workflows)
2. Add

content_status: [draft, published]

under matchers
3. Create a new article. You will see a "Send to Design" icon which works as expected.
4. Publish an article. Edit the Article to create a new draft. There is no "Send to Design" icon in the new draft.

5. Change the content_status config to

[published, draft]

6. Create and publish a new article. Edit the Article to create a new draft. You will see a "Send to Design" icon which works as expected.
7. Create a new article. Click the "Send to Design" icon. You will see a 500 error (see attachment).