ngx-charts dispatchAction not updating chart if echart directive is used in ng-template

Question

I am using Angular and ngx-echarts v16.

I have a chart component library that uses ngx-echarts and it works great. I can put the directive in a reusable ng-template and the chart displays correctly and the initChart function is called, where I assign the chart to a variable in the component:

  initChart(event: ECharts): void {
    console.log("initChart");
    this.chart = event;
  }

<div class="dashboard-card">
  <ng-container *ngTemplateOutlet="contentTemplate"></ng-container>
</div>

<cpx-maximised [(visible)]="fullscreen" [header]="header" *ngIf="maximisable">
  <ng-container *ngTemplateOutlet="contentTemplate"></ng-container>
</cpx-maximised>

<ng-template #contentTemplate>
  <div class="content-row">
    <div class="legend" *ngIf="showLegend">
      <div class="legend-item" (click)="toggleSelected(c.name)" *ngFor="let c of legendItems"
        [ngClass]="{'unselected': !c.enabled}">
        <div class="circle" [ngStyle]="{'background': !c.enabled ? 'rgba(0, 0, 0, 0.1)' :  c.rgbColour}">
        </div>{{c.name}}
      </div>
    </div>
    <div class="chart-container">
      <div echarts [autoResize]="true" [options]="defaultOptions" [merge]="updatedChartOptions" class="chart"
        (chartInit)="initChart($event)">
      </div>
    </div>
  </div>
</ng-template>

In the above example I have a simple custom legend that calls a function that dispatches an action to toggle the legend item as such:

  toggleSelected(seriesName: string): void {
    this.chart.dispatchAction({
      type: "legendToggleSelect",
      name: seriesName,
    });

    const legendItemIndex = this.legendItems.findIndex(
      (x) => x.name === seriesName
    );
    this.legendItems[legendItemIndex].enabled =
      !this.legendItems[legendItemIndex].enabled;
  }

However, nothing happens when the action is dispatched, I assume because it can't find the chart object!

If I refactor the above view so that the chart is not in a template everything works perfectly albeit I have to manage 2 chart instances, which isn't the end of the world but I feel like I might be missing something obvious.

n.b. if I use the standard legend everything works fine but that doesn't work for me really and also the above is just an example of one particular action being dispatched.