AEP Data stream target mapping for device, environment, web from xdm object not working

I have the below network request 

{
  "events": [
    {
      "xdm": {
        "eventType": "web.webpagedetails.pageViews",
        "web": {
          "webPageDetails": {
            "URL": "https://www.xyz.com"
          },
          "webReferrer": {
            "URL": "https://www.xyz.com"
          }
        },
        "device": {
          "screenHeight": 800,
          "screenWidth": 1280,
          "screenOrientation": "landscape"
        },
        "environment": {
          "type": "browser",
          "browserDetails": {
            "viewportWidth": 1265,
            "viewportHeight": 150
          }
        },
        "placeContext": {
          "localTimezoneOffset": -330,
          "localTime": "2026-05-08T09:54:09.711+05:30",
          "ianaTimezone": "Asia/Calcutta"
        },
        "timestamp": "2026-05-08T04:24:09.714Z",
        "implementationDetails": {
          "name": "https://ns.adobe.com/experience/alloy/reactor",
          "version": "__VERSION__+2.34.2",
          "environment": "browser"
        },
        "_myprojectname": {
          "testobject": {
            "webPageDetails": {
              "title": "test page",
              "referralSource": "abc"
            }
          }
        }
      },
      "query": {
        "personalization": {
          "schemas": [
            "https://ns.adobe.com/personalization/default-content-item",
            "https://ns.adobe.com/personalization/html-content-item",
            "https://ns.adobe.com/personalization/json-content-item",
            "https://ns.adobe.com/personalization/redirect-item",
            "https://ns.adobe.com/personalization/ruleset-item",
            "https://ns.adobe.com/personalization/message/in-app",
            "https://ns.adobe.com/personalization/message/content-card",
            "https://ns.adobe.com/personalization/dom-action"
          ],
          "decisionScopes": [
            "__view__"
          ],
          "surfaces": [
            "web://xyz.com/webApp/test"
          ]
        }
      }
    }
  ],
  "query": {
    "identity": {
      "fetch": [
        "ECID",
        "CORE"
      ]
    }
  },
  "meta": {
    "queueTimeMillis": 6,
    "state": {
      "domain": "adobe.com",
      "cookiesEnabled": true,
      "entries": [
        {
          "key": "kndctr_1A6727E2_AdobeOrg_identity",
          "value": "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx=="
        }
      ]
    }
  }
}

For this I have created the schema where the entire webPageDetails fall under “testobject”.

And post that I have done the target mapping 

events[*].xdm.web.webPageDetails.URL   → _myprojectname.testobject.webPageDetails.URL  

But with above the field does not get populated but if I change to the below it starts working as expected.

events[*].xdm.web.webPageDetails.URL   → web.webPageDetails.URL  

Any pointers will be helpful.

Thanks