How to reproduce:

• Create a SystemProperty of type content
  • Add this property in search model select-content (in plugin Web if needed)), in columns
  • Make some contents to have the system property filled
• Open a content with an attribute of type content
• Modify the content
  • On attribute of type content, click on search button and search for contents.
    • A column of the new system property appears => OK
    • But the column is empty => KO