Why are Attributes in Nested Enities not evaluated when matching?

Question

we are using Marklogic DataHub QuickStart Version 5.1.0 for Mastering customer data into a Golden Record. The Entity Structure where we have problems with looks like this

{
  "envelope": {
    "instance": {
      "customer": {
        "lastname": "Examplelast",
        "firstname": "Examplefirst",
        "phonenumbers": [
          {
            "phone": {
              "number": "1234567890",
              "ismobil": "true"
            }
          },
          {
            "phone": {
              "number": "9876543210",
              "ismobil": "false"
            }
          }
        ]
      }
    }
  }
}

The Match Options definition looks like this

{
  "matchOptions": {
    "propertyDefs": {
      "property": [
        {
          "localname": "lastname",
          "name": "lastname"
        },
        {
          "localname": "firstname",
          "name": "firstname"
        },
        {
          "localname": "phone.number",
          "name": "phone.number"
        }
      ]
    },
    "scoring": {
      "add": [
        {
          "propertyName": "lastname",
          "weight": "5"
        },
        {
          "propertyName": "firstname",
          "weight": "5"
        },
        {
          "propertyName": "phone.number",
          "weight": "25"
        }
      ]
    }
  }
}

The first problem is that we can´not select the "number" attributes from the Match Options (only "phonenumbers" can be selected. So we edit the flow file on system level, writing "phone.number" with the weight definition to the file (can not be edit via the UI afterwards). Starting the flow, we receive no error but also no match for the "phone.number" after the run.

Any ideas how to solve this topic? Many thanks Andreas