My bad... and of that Youtube video. I had made those uuids in the bundle reckonlessly which caused the failure of resolving the references in IRIS. After I have corrected them into proper ones, that works!!

Having modified a bit the FHIR bundle transaction and tested again. This time it helped prevent having the same Patient resource created twice, which is already good enough for me.

But the "fullUrl" reference of the Patient resource still cannot get resolved with the logical reference. I'm a bit disappointed with that the value of the "subject"."reference of the ServiceRequest got unchanged.

Here is the FHIR Bundle Transaction sent to /csp/healthshare/fhirserver/fhir/r4 (places bold are those modified):

{
    "resourceType": "Bundle",
    "type": "transaction",
    "entry": [
        {
            "fullUrl": "urn:uuid:patient",
            "resource": {
                "resourceType": "Patient",
                "active": true,
                "birthDate": "1970-04-12",
                "gender": "female",
                "identifier": [
                    {
                        "type": {
                            "coding": [
                                {
                                    "system": "http://myterminology.com",
                                    "code": "1001949"
                                }
                            ]
                        },
                        "use": "usual",
                        "value": "A1234563"
                    }
                ],
                "name": [
                    {
                        "family": "CHAN",
                        "given": [
                            "CLARA"
                        ],
                        "use": "official"
                    }
                ]
            },
            "request": {
                "method": "POST",
                "url": "Patient",
                "IfNoneExist": "identifier=A1234563"
            }
        },
        {
            "resource": {
                "resourceType": "ServiceRequest",
                "requisition": {
                    "system": "http://myexample.com",
                    "value": "H2302-10648"
                },
                "status": "active",
                "intent": "original-order",
                "category": [
                    {
                        "coding": [
                            {
                                "system": "http://snomed.info/sct",
                                "code": "108252007"
                            }
                        ]
                    }
                ],
                "priority": "routine",
                "code": {
                    "coding": [
                        {
                            "system": "http://myexample.com",
                            "code": "CBC"
                        }
                    ]
                },
                "subject": {
                    "type": "Patient",
                    "reference": "urn:uuid:patient"
                },
                "authoredOn": "2023-02-08T08:40:00+08:00"
            },
            "request": {
                "method": "POST",
                "url": "ServiceRequest"
            }
        }
    ]
}

And here is the response of the HTTP GET from /csp/healthshare/fhirserver/fhir/r4/ServiceRequest/53 for viewing the ServiceRequest resource after having the FHIR bundle submitted (note that the reference of "subject" in the ServiceRequest resource does not resolve into a logical reference):

{
    "resourceType": "ServiceRequest",
    "requisition": {
        "system": "http://myexample.com",
        "value": "H2302-10648"
    },
    "status": "active",
    "intent": "original-order",
    "category": [
        {
            "coding": [
                {
                    "system": "http://snomed.info/sct",
                    "code": "108252007"
                }
            ]
        }
    ],
    "priority": "routine",
    "code": {
        "coding": [
            {
                "system": "http://myexample.com",
                "code": "CBC"
            }
        ]
    },
    "subject": {
        "type": "Patient",
        "reference": "urn:uuid:patient"
    },
    "authoredOn": "2023-02-08T08:40:00+08:00",
    "id": "53",
    "meta": {
        "lastUpdated": "2023-02-16T15:39:14Z",
        "versionId": "1"
    }
}

And here is the response of the HTTP GET from /csp/healthshare/fhirserver/fhir/r4/Patient/52 for viewing the Patient resource: