Dependant for editor - Separate script not populated select list

I have two dependant selects on my Editor. One is working fine, the new one (assessments) is not working:

This is the separate script to get assessments when the learning_event.unit_group_fk select is selected:

<?php
require_once( '../../../maps/cm_mjd_plmed/connection/connect.php' );

$unit = $_POST['values']['learning_event.unit_group_fk'];

$data = array();

$query = "SELECT * FROM assessment WHERE unit_group_fk = '$unit'";
$result = $connection->query( $query );

while ($row = mysqli_fetch_array($result)) {
    $data[] = array("label"=>$row['assessment'], "value"=>$row['assessment_pk']);
}

$temp = array('assessment[].assessment_pk'=>$data);
$json = array('options'=>$temp);
echo json_encode($json);
?>

The client side:

        <div id="learning_event_form">
            <editor-field name="learning_event.learning_event_name"></editor-field>
            <editor-field name="learning_event.outline"></editor-field>
            <editor-field name="learning_event.length"></editor-field>
            <editor-field name="program_outcome[].program_outcome_pk"></editor-field>
            <editor-field name="learning_event.unit_group_fk"></editor-field>
            <editor-field name="learning_event.week_fk"></editor-field>
            <editor-field name="assessment[].assessment_pk"></editor-field>
            <editor-field name="learning_event_type[].learning_event_type_pk"></editor-field>
        </div>

var editor = new $.fn.dataTable.Editor( {
                ajax: "program_data/learning_event_data.php",
                table: "#learning_event_table",
                template: '#learning_event_form',
                fields: [ {
                    label: "Learning Event:",
                    name: "learning_event.learning_event_name"
                }, {
                    label: "Outline:",
                    name: "learning_event.outline",
                    type: "ckeditor"
                },{
                    label: "Length (minutes):",
                    name: "learning_event.length"
                }, {
                    label: "Program Outcome:",
                    name: "program_outcome[].program_outcome_pk",
                    type: "select",
                    placeholder: 'No selection',
                    placeholderDisabled: false,
                    placeholderValue: 0,
                    multiple: true
                }, {
                    label: "Unit Group:",
                    name: "learning_event.unit_group_fk",
                    type: "select",
                    placeholder: "Select Unit Group..."
                }, {
                    label: "Week:",
                    name: "learning_event.week_fk",
                    type: "select",
                    placeholder: "Select Week..."
                },{
                    label: "Assessment:",
                    name: "assessment[].assessment_pk",
                    type: "select",
                    placeholder: "Select Assessments...",
                    placeholderDisabled: false,
                    placeholderValue: 0,
                    multiple: true
                }, {
                    label: "Type:",
                    name: "learning_event_type[].learning_event_type_pk",
                    type: "select",
                    placeholder: 'No selection',
                    placeholderDisabled: false,
                    placeholderValue: 0,
                    multiple: true,
                        attr: {
                            size: 1
                        }
                } ]
            } );
            
            
            
                editor.dependent('learning_event.unit_group_fk', 'program_data/get_weeks.php');
            
                editor.dependent('learning_event.unit_group_fk', 'program_data/get_assessments.php');
            
            

            var table = $( '#learning_event_table' ).DataTable( {
                responsive: true,
                "autoWidth": false,
                "lengthMenu": [
                    [ 5, 10, 25, 50, -1 ],
                    [ 5, 10, 25, 50, "All" ]
                ],
                columnDefs: [ {
                    targets: 1,
                    render: $.fn.dataTable.render.ellipsis( 150, true )
                } ],
                ajax: "program_data/learning_event_data.php",
                dom: "Blfrtip",
                columns: [ {
                    data: "learning_event.learning_event_name",
                }, {
                    data: "learning_event.outline",
                }, {
                    data: "learning_event.length",
                }, {
                    data: "program_outcome",
                    render: "[, ].program_outcome"
                }, {
                    data: "unit_group.unit_group"
                }, {
                    data: "week.week_full_name"
                }, {
                    data: "assessment.assessment",
                    render: "[, ].assessment"
                }, {
                    data: "learning_event_type",
                    render: "[, ].learning_event_type_name"
                }, {
                    data: "learning_event.modified"
                }, {
                    data: "learning_event.modified_by"
                }, {
                    data: null,
                    className: "center",
                    defaultContent: '<a href="" class="editor_edit">Edit</a>'
                } ],
                select: {
                    style: 'os',
                    selector: 'td:first-child'
                },
                buttons: []
            } );