One-to-many checkboxes in standalone example

I am trying to combine these two examples, https://editor.datatables.net/examples/advanced/joinArray.html and https://editor.datatables.net/examples/standalone/simple.html, to create a standalone editor which uses one-to-many checkboxes.

I understand that when using the standalone editor the additional options data is not loaded so you must load it separately, I have done this and it almost works. All my checkboxes load correctly but the selected checkboxes, i.e the ones which should show a tick, does not work with multiple selected values. So it is the pre-selected values which isn't working for multiple values.

If anyone can point me in the right direction that would be great.

        var editor;  
         
        $(document).ready(function() {
            editor = new $.fn.dataTable.Editor( {
                ajax : {
                    url : "/modules/DataTables/action.run_datatable.php",
                    type : "POST",
                },
                fields: [{
                    label : "Categories:*",
                    name : "system_resource_category[].resource_category_id",
                    type : "checkbox"
                }]
            });    
            editor.on('open', function() {  

                var optionsI = [];
                var optionI = $("span#optionI").attr("data-editor-value");
                $.ajax({
                    type : 'POST',
                    url : '/modules/DataTables/action.run_datatable.php',
                    dataType: 'json',
                    data : { 
                        table: 'system_resource_category',                                                           
                    },
                    success : function(response) {
                        var option = {};
                        $.each(response['data'], function (i, e) {
                            option.label = e.system_resource_category['name'];
                            option.value = e.system_resource_category['resource_category_id'];
                            optionsI.push(option);
                            option = {};
                        });  
                        editor.field('system_resource_category[].resource_category_id').update(optionsI).val(optionI);           
                    } 
                }); 

                editor.on( 'submitSuccess', function ( e, json, data, action ) {
                    var categories = json['data']['0']['system_resource_category'].map(function(entry) { return entry.name; }).join(', ');                    
                    $('[data-editor-field="system_resource_category[].resource_category_id"]').text(categories);
                }); 

            });
            
        });

<tr><td> Categories: </td><td> <span id="optionI" data-editor-field="system_resource_category[].resource_category_id" data-editor-value="8, 7">Hillwalking and Navigation Courses, Winter Courses</span> </td></tr>

Thanks

Chris