Rest API Registry Size is null

I am trying to get the size of a repository via rest api.
Following this documentation: Container Registry API | GitLab

However the size is always null.

From the project container regsitry page in my Gitlab:

Name       Size   
         
2          347.72 MiB  Published 2 days ago  Digest: d90160f

latest     348.84 MiB   Published 2 days ago Digest: 9653a95
API Call: https://gitlab.eee.net/registry/repositories/42/?per_page=100&page=1&tags=true&tags_count=true&size=true

{
  "id": 42,
  "name": "",
  "path": "eee/sysinfo",
  "project_id": 627,
  "location": "registry.eee.net/eee/sysinfo",
  "created_at": "2023-05-12T11:17:45.099Z",
  "cleanup_policy_started_at": null,
  "tags_count": 2,
  "tags": [
    {
      "name": "2",
      "path": "eee/sysinfo:2",
      "location": "registry.eee.net/eee/sysinfo:2"
    },
    {
      "name": "latest",
      "path": "eee/sysinfo:latest",
      "location": "registry.eee.net/eee/sysinfo:latest"
    }
  ],
  "delete_api_path": "https://gitlab.eee.net/api/v4/projects/627/registry/repositories/42",
  "size": null
}

What is going wrong?

Kind regards