Hi @Akuma Isaac I'm able to reproduce this issue. Can you help me understand what response you are expecting by sorting on

split_members_development.created_at

? Let's take this example:

{"name": "foo", "members": ["user_a", "user_b", "user_c"]}
{"name": "bar", "members": ["user_b"]}

and the following members:

{"user_id": "user_a","created_at": 10}
{"user_id": "user_b","created_at": 5}
{"user_id": "user_c","created_at": 15}

If you won't mention

sort_by

you'll receive the following response:

{
  "results": [
    {
      "facet_counts": [],
      "found": 2,
      "hits": [
        {
          "document": {
            "id": "1",
            "members": [
              "user_b"
            ],
            "name": "bar",
            "split_members_development": [
              {
                "created_at": 5,
                "id": "1",
                "user_id": "user_b"
              }
            ]
          },
          "highlight": {},
          "highlights": []
        },
        {
          "document": {
            "id": "0",
            "members": [
              "user_a",
              "user_b",
              "user_c"
            ],
            "name": "foo",
            "split_members_development": [
              {
                "created_at": 10,
                "id": "0",
                "user_id": "user_a"
              },
              {
                "created_at": 5,
                "id": "1",
                "user_id": "user_b"
              },
              {
                "created_at": 15,
                "id": "2",
                "user_id": "user_c"
              }
            ]
          },
          "highlight": {},
          "highlights": []
        }
      ],
      "out_of": 2,
      "page": 1,
      "request_params": {
        "collection_name": "splits_development",
        "first_q": "*",
        "per_page": 10,
        "q": "*"
      },
      "search_cutoff": false,
      "search_time_ms": 0
    }
  ]
}

What response are you expecting when you mention

"sort_by": "$split_members_development(created_at:desc)"

?