Power BI中Deneb径向仪表盘度量值设置填充色失效问题

我尝试使用度量值colorcode（取值为#d23d96）修改Deneb径向仪表盘的填充色，能在数据表中看到该度量值的数据，但无法将其应用到仪表盘上。代码第103行是填充色设置位置，手动输入颜色值时生效，但引用度量值colorcode就无效。

以下是仪表盘的完整代码：

{
  "name": "RADIAL_GAUGE",
  "data": { "name": "dataset" },
  "transform": [
    {
      "calculate": "360 - ( datum['Degrees'] / 2 )",
      "as": "_arc_start_degrees"
    },
    {
      "calculate": "0 + ( datum['Degrees'] / 2 )",
      "as": "_arc_end_degrees"
    },
    {
      "calculate": "2 * PI * ( datum['_arc_start_degrees'] - 360 ) / 360",
      "as": "_arc_start_radians"
    },
    {
      "calculate": "2 * PI * datum['_arc_end_degrees'] / 360",
      "as": "_arc_end_radians"
    },
    {
      "calculate": "datum['_arc_end_radians'] - datum['_arc_start_radians']",
      "as": "_arc_total_radians"
    },
    {
      "calculate": "datum['_arc_start_radians']",
      "as": "_ring_start_radians"
    },
    {
      "calculate": "datum['_arc_start_radians'] + ( datum['_arc_total_radians'] * datum['Percent'] )",
      "as": "_ring_end_radians"
    }
  ],
  "params": [
    { "name": "ring_max", "value": 160 },
    { "name": "ring_width", "value": 20 },
    { "name": "ring_gap", "value": 5 },
    { "name": "ring0_color", "value": "#FFFFFF" },
    { "name": "label_color", "value": "#000000" },
    { "name": "ring_background_opacity", "value": 0.3 },
    { "name": "ring0_percent", "value": 100 },
    { "name": "ring0_outer", "expr": "ring_max+2" },
    { "name": "ring0_inner", "expr": "ring_max+1" },
    {
      "name": "ring1_outer",
      "expr": "ring0_inner-ring_gap"
    },
    {
      "name": "ring1_inner",
      "expr": "ring1_outer-ring_width"
    },
    {
      "name": "ring1_middle",
      "expr": "(ring1_outer + ring1_inner) / 2"
    }
  ],
  "layer": [
    {
      "name": "RING OPAQUE BACKGROUND",
      "mark": {
        "type": "arc",
        "radius": {
          "expr": "ring1_outer"
        },
        "radius2": {
          "expr": "ring1_inner"
        },
        "theta": {
          "expr": "datum['_arc_start_radians']"
        },
        "theta2": {
          "expr": "datum['_arc_end_radians']"
        },
        "cornerRadius": 0
      },
      "encoding": {
        "color": {
          "value": "#CCCCCC"
        },
        "opacity": {
          "value": {
            "expr": "ring_background_opacity"
          }
        }
      }
    },
    {
      "name": "RING",
      "mark": {
        "type": "arc",
        "radius": {
          "expr": "ring1_outer"
        },
        "radius2": {
          "expr": "ring1_inner"
        },
        "theta": {
          "expr": "datum['_ring_start_radians']"
        },
        "theta2": {
          "expr": "datum['_ring_end_radians']"
        },
        "fill": "colorcode",
        "cornerRadius": 0
      },
      "encoding": {
        "color": {
          "field": "colorcode",
          "type": "nominal"
        }
      }
    },
    {
      "description": "VALUE",
      "mark": {
        "type": "text",
        "fontSize": 60
      },
      "encoding": {
        "text": {
          "field": "Percent",
          "type": "quantitative",
          "formatType": "pbiFormat",
          "format": "0%"
        },
        "color": {
          "value": {
            "expr": "label_color"
          }
        }
      }
    }
  ]
}

内容的提问来源于stack exchange，提问作者Anton Pazuslkyi