can't get legendCallback to fire at all

[ssuess]

Expected Behavior

legendCallback should fire when this._chart.generateLegend() is called.

Actual Behavior

Can't get it to fire.

My charts display, and a generic legend is being generated and shown, but my legendCallback is being ignored, it is not firing. My console.log line ('legCallback') shows nothing. But I know the generateLegend method is working because my (generic) legend shows in my div.

Here is my code:

mounted () {
this.renderChart(this.pielabels, {
      responsive: true,
      maintainAspectRatio: false,
      legendCallback: function (chart) {
        var text = []
        console.log('legCallback')
        text.push('<div>')
        for (var i = 0; i < chart.data.datasets.length; i++) {
          text.push('<li><span style=\'background-color:#333\'>')
          text.push(chart.data.datasets[i].label)
          text.push('</span></li>')
        }
        text.push('</div>')
        return text.join('')
      },
      legend: {
        display: false
      },
      titleFontStyle: 'bold'
    })
    this.$bus.$emit('legendgen', this._chart.generateLegend())
  }