@y.bruyere

From my checking, the Identifier in the Search/FundSearch only supports one instrument.

You can use other methods to get OrgId.

1. Using Search/InstrumentSearch

{
  "SearchRequest": {
    "InstrumentTypeGroups": [
      "Funds"
    ],
    "IdentifierType": "Isin",
    "Identifier": "IE00B6X2JP23,TEST,LU1542443954",
    "PreferredIdentifierType": "OrgId"
  }
}

The output is:

 [
        {
            "Identifier": "105338777",
            "IdentifierType": "NONE",
            "Source": "LIP",
            "Key": "VjF8MHgwMDAzZjgwNmVmZDNmYzNkfDB4MDAwM2Y4MDZlZmQzZmMzZHxMSVB8TUZRVXxNVExGfE1UTEZ8Rnx8TFA2ODE1Njk1MHxGVU5E",
            "Description": "Comgest Growth Amer EUR R Acc",
            "InstrumentType": "MutualFundQuote",
            "Status": "Valid"
        },
        {
            "Identifier": "109086845",
            "IdentifierType": "NONE",
            "Source": "LIP",
            "Key": "VjF8MHgwMDAzZjgxNjJmODc5M2Q2fDB4MDAwM2Y4MTYyZjg3OTNkNnxMSVB8TUZRVXxNVExGfE1UTEZ8Rnx8TFA2ODQxMDc5NHxGVU5E",
            "Description": "LOF - All Roads EUR NA",
            "InstrumentType": "MutualFundQuote",
            "Status": "Valid"
        }
    ]

2. Using other report templates that provide the OrgId content field, such as TermsAndConditionsExtractionRequest.

{
    "ExtractionRequest": {
        "@odata.type": "#DataScope.Select.Api.Extractions.ExtractionRequests.TermsAndConditionsExtractionRequest",
        "ContentFieldNames": [
           "RIC", "CUSIP", "ISIN", "SEDOL", "Issuer OrgID", "Currency Code"
        ],
        "IdentifierList": {
            "@odata.type": "#DataScope.Select.Api.Extractions.ExtractionRequests.InstrumentIdentifierList",
            "InstrumentIdentifiers": [
                { "Identifier": "IE00B6X2JP23", "IdentifierType": "Isin" },              
                { "Identifier": "LU1542443954", "IdentifierType": "Isin" }              
            ]
        }
    }
}

The output is:

[
        {
            "IdentifierType": "Isin",
            "Identifier": "IE00B6X2JP23",
            "RIC": "LP68156950",
            "CUSIP": null,
            "ISIN": "IE00B6X2JP23",
            "SEDOL": "B6X2JP2",
            "Issuer OrgID": "105338777",
            "Currency Code": "EUR"
        },
        {
            "IdentifierType": "Isin",
            "Identifier": "LU1542443954",
            "RIC": "LP68410794",
            "CUSIP": null,
            "ISIN": "LU1542443954",
            "SEDOL": null,
            "Issuer OrgID": "109086845",
            "Currency Code": "EUR"
        }
    ]

You can refer to the Refinitiv DataScope Select Data Content Guide to find which report templates provide the OrgID content fields.