Hi John,

Firstly, I would like to sincerely apologize for the delayed response as we have been experiencing an unusually high number of tickets. I am sorry that it has taken longer than usual to respond to your concern and your patience is highly appreciated.

-

I just did a small Test of this Use-Case by inserting a blank row of Data in a Google Sheet, like this :

If i disable Sorting on my linked Table, then it just sorts the Values as i inserted them from the Sheet, as intended :

And you are correct, in our Chart.JS Line Chart, this data is presented as simply being at a zero point, and it is connected to the rest of the series points, like this :

That is the default behaviour of the Chart Engine itself.

We use free libraries for chart engines, and they are limited as to what we can change from within the plugin's UI.

We do no have a built-in option to set the X axis to 'separate' that section with the blank row from the rest/to 'disconnect' them such as in your example.

To achieve that, you can only try to find a custom solution using chart callbacks.

You can check our documentation about wpDataCharts callbacks. 

• Every chart exposes several options that customize its look and feel. Charts usually support custom options appropriate to that visualization. wpDataChart callbacks allow adding options that are available in Google Charts API, Highcharts API, and Chart.js API. 

• All necessary resources are available in charts engines API (depends on which one you use).
  Every engine has a different approach to chart settings. In wpDataChart callbacks, you have to adopt those settings to the wpDataChart object (you can take a look at examples for each engine in our documentation, and also in the Support help center).
  A huge number of examples for any area of programming can be found on stackoverflow.com (typing your problem in google and at the end add "site: stackoverflow.com" and Google will search only that website).
  Also, a lot of examples of charts, chart settings, and customization can be found on jsffidle.net (typing in google for example "line chart highcharts jsffidle")
• Please note that using hooks or wpDataTable and wpDataChart callbacks requires a certain level of programming skills and included support refers only to advice.

-

When it comes to custom examples we have at the moment, i will share one where you can "skip NULL or blank values" on Chart series, i realise that is the opposite of what you wish to achieve, but i hope it might help at least as a starting example :

Please note that this workaround only works for HighCharts Engine.

For other Chart Engines we don't currently have a workaround to skip NULL and/or zero values.

If you wish to try it, please go to the functions.php file of your theme or child theme, and add this:

function filterNullValues ($value, $origHeader ,$chartID, $tableID){
     // You can add conditions for specific org header, chart id or table id
    // Here we only check if value is null and provide same value to the chart object
    if (is_null($value) || $value == 0 || intval($value) == 0){
        $value = null;
    }
    return $value;
}
add_filter( 'wpdatatables_filter_int_cell_data_in_charts', 'filterNullValues', 10, 4 );
add_filter( 'wpdatatables_filter_float_cell_data_in_charts', 'filterNullValues', 10, 4 );

This works for integer and float columns that have NULL values and "0" values.

If you want to apply it just for NULL values, you can use this code:

function filterNullValues ($value, $origHeader ,$chartID, $tableID){
     // You can add conditions for specific org header, chart id or table id
    // Here we only check if value is null and provide same value to the chart object
    if (is_null($value)){
        $value = null;
    }
    return $value;
}
add_filter( 'wpdatatables_filter_int_cell_data_in_charts', 'filterNullValues', 10, 4 );
add_filter( 'wpdatatables_filter_float_cell_data_in_charts', 'filterNullValues', 10, 4 );

And if you want to apply it just for "0" values, you can use this code:

function filterNullValues ($value, $origHeader ,$chartID, $tableID){
     // You can add conditions for specific org header, chart id or table id
    // Here we only check if value is null and provide same value to the chart object
    if ($value == 0){
        $value = null;
    }
    return $value;
}
add_filter( 'wpdatatables_filter_int_cell_data_in_charts', 'filterNullValues', 10, 4 );
add_filter( 'wpdatatables_filter_float_cell_data_in_charts', 'filterNullValues', 10, 4 );

You don't need to change the code after the plugin updates, but you will need to keep this code in functions.php.

If you want to connect data with NULLs skipped, you can use this callback: https://jsfiddle.net/gh/get/library/pure/highcharts/highcharts/tree/master/samples/highcharts/plotoptions/series-connectnulls-true/

<script type="text/javascript">
jQuery(window).on('load',function(){
    if( typeof wpDataChartsCallbacks == 'undefined' ){ wpDataChartsCallbacks = {}; }
    wpDataChartsCallbacks[16] = function(obj){
        obj.options.plotOptions = {
            series: {
                connectNulls: true
            }
        }
    };
});
</script>

Just make sure to replace [16] with the ID of your chart.

As mentioned earlier, this only works for the HighCharts Engine;

   and I realise that is not what you're trying to achieve, but I hope that this, in combination with other details shared above, might serve as a starting point.

I hope that helps.