Wrong graph after .update()

[kreare]

Hi all.
I'm on 2.9.x (can't upgrade right now)
I've seen a strange behaviour that i can't explain.

I have a function that fetch some datas from an API and then fill the graph.
On first access, the graph is shown as expected.
When I change the date range from a calander in the webpage and I re-call the exact same function (it takes 2 parameters in input: startDate and endDate), datas are retrieved successfully, but the graph doesn't show the proper values.

This is the function:

function loadChartData(start, end) {
    totalsChart.config.data.labels.length = 0
    totalsChart.config.data.datasets.forEach((dataset) => {
        dataset.data.pop()
    })
    totalsChart.update();

    console.log('start='+start+', end='+end);

    $.getJSON('/xxxx?start=' + start + '&end=' + end).done(function( data ) {
        console.log(data);

        totals = data.totals;

        $.each(totals, function(key, value){
            let totals = 0
            var giorno = moment(key, "YYYYMMDD").format('ddd, D MMM');
            totalsChart.config.data.labels.push(giorno);
            for ( var i = 0; i < value.length; i++ ) {
                totalsChart.config.data.datasets[i].data.push(value[i]);
                totals += value[i]
            }
            totalsChart.config.data.datasets[ 5 ].data.push(totals)
        });
        totalsChart.update();
    });
}

It's the same called on page opening (and graph is shown properly) and on date change.
What I saw is that If I remove the totalsChart.config.data.labels.length = 0 , the new data is shown properly, but appended to the current graph. If I reset the lables, NEW data are shown wrong.

So, probably there is something that i'm doing wrong when I have to totally-reset the graph.

Any idea ?

[kreare]

What i've understood is that if the graph on page load starts with 2025-11-01 to 2025-11-15 (in example), even If change the date range to something like 2025-11-10 to 2025-11-15, data shown is still the one at 2025-11-01 (the first point loaded with the first graph).