Why does this happen (sometimes) to my Apex Charts graph?

I’m plotting the hourly consumption in purple, it usually works but sometimes this happens.
Does anyone have any idea what it could be that causes it?

      - entity: sensor.last_meter_consumption_osthammar
        yaxis_id: kWh
        type: column
        name: Usage
        color: '#932bd9'
        float_precision: 1
        stroke_width: 2
        offset: '-1h'
        group_by:
          func: delta
          duration: 1hour