I've had the same issue. I believe it stems from the ng-mdb-pro/typoescripts/free/charts/chart.directive.ts file in the ngOnChanges() method.

Start your code here

public ngOnChanges(changes: SimpleChanges): void {
if (this.initFlag) {
// Check if the changes are in the data or datasets
if (changes.hasOwnProperty('data') || changes.hasOwnProperty('datasets')) {
if (changes['data']) {
this.updateChartData(changes['data'].currentValue);
} else {
this.updateChartData(changes['datasets'].currentValue);
}

this.chart.update();
} else {
// otherwise rebuild the chart
this.refresh();
}
}
}

For some reason, I can't get it to trigger this.refresh(). This means we're stuck updating the current chart vs. redrawing the whole thing with the changed x-axis items. Super frustrating, especially because the y-axis adjusts dynamically.