My Identity Schema (note that

phone

is in the traits). I've also tried changing the key to `phone_number`:

{
  "$id": "<https://schemas.ory.sh/presets/kratos/identity.email.schema.json>",
  "title": "Person",
  "type": "object",
  "properties": {
    "traits": {
      "type": "object",
      "properties": {
        "email": {
          "type": "string",
          "format": "email",
          "title": "E-Mail",
          "ory.sh/kratos": {
            "credentials": {
              "password": {
                "identifier": true
              },
              "webauthn": {
                "identifier": true
              },
              "totp": {
                "account_name": true
              },
              "code": {
                "identifier": true,
                "via": "email"
              }
            },
            "recovery": {
              "via": "email"
            },
            "verification": {
              "via": "email"
            }
          },
          "maxLength": 320
        },
        "name": {
          "type": "object",
          "required": [
            "first",
            "last"
          ],
          "properties": {
            "first": {
              "title": "First name",
              "type": "string"
            },
            "last": {
              "title": "Last name",
              "type": "string"
            }
          }
        },
        "phone": {
          "title": "Phone (with country code)",
          "type": "string",
          "format": "tel"
        }
      },
      "required": [
        "email"
      ],
      "additionalProperties": false
    }
  }
}