echarts的treeMap使用rich自定义富文本样式后无法使用verticalAlign:"middle"垂直居中

<template>
  <div>
    <div ref="chart" style="width: 600px; height: 400px;"></div>
  </div>
</template>

<script>
import echarts from 'echarts';

export default {
  mounted() {
    this.initChart();
  },
  methods: {
    initChart() {
      const chartDom = this.$refs.chart;
      const myChart = echarts.init(chartDom);

      const data = [
        { value: 100, name: 'Category 1' },
        { value: 200, name: 'Category 2' },
        // ... more data
      ];

      const option = {
        series: [
          {
            type: 'treemap',
            data: data,
            label: {
              show: true,
              formatter: (params) => {
                return `{a|${params.name}}\n\n{b|${params.value}}`;
              },
              rich: {
                a: {
                  fontSize: 16,
                  lineHeight: 24,
                  verticalAlign: 'middle',
                },
                b: {
                  fontSize: 14,
                  lineHeight: 24,
                  verticalAlign: 'middle',
                },
              },
            },
          },
        ],
      };

      myChart.setOption(option);
    },
  },
};
</script>