I have a custom field defined like that:

{
  "quackgames:helpers": {
    "name": "Helpers",
    "type": "users",
    "search": true
  }
}

I try to make a custom query in maniphest to see all task that don't have any "Helpers" associated to it. When I give no value, it don't filter anything, and there no "No one" option!

Is there a way to do this or something similar? Thanks.