Can't create Page Provider form layout for Document Page

Steps to Reproduce:

• On nos-test
• Follow steps indicated in this tutorial: https://doc.nuxeo.com/nxdoc/how-to-new-pill/
• Missing steps at end:
  • Go to Page Providers > otherContracts
  • Click on Results > Configure
  • Click Save.
  • Click on Forms > Configure
    => Nothing happens
• Deploy on Nuxeo instance.
  => Layout appears.