emptyCell on the filter row

Hi,
I have 'emptyCell' => 'None set', set on a GridView widget (full code shown below). The cell that corresponds to the filter row and the actioncolumn displays this text.

How do I override that?

TIA, Nic

    <?= GridView::widget([
        'dataProvider' => $dataProvider,
        'filterModel' => $searchModel,
        'columns' => [
            [
                'class' => ActionColumn::className(),
                'urlCreator' => function ($action, Device $model, $key, $index, $column) {
                    return Url::toRoute([$action, 'id' => $model->id]);
                },
                'header' => 'Row Actions',
                'headerOptions' => ['class' => 'col-2 text-center'],
                'contentOptions' => ['class' => 'text-center'],
            ],
            [
                'attribute' => 'id',
                'label' => 'Device ID',
                'headerOptions' => ['class' => 'col-2'],
            ],
            //'id',
            [
                'attribute' => 'device_type_id',
                'label' => 'Type',
                'value' => 'deviceType.name',
                'headerOptions' => ['class' => 'col-4'],
            ],
            //'device_type_id',
            [
                'attribute' => 'active',
                //'value' => 'active', // display 1/0 because format missing
                'format' => 'boolean',
                'label' => 'Active',
                'filter' => [0 => 'No', 1 => 'Yes'],
                'filterInputOptions' => ['prompt' => 'Filter list on...', 'class' => 'form-control'],
                'headerOptions' => ['class' => 'col-2'],
            ],
        ],
        'emptyCell' => 'None set', // puts this text in the filter row for actionColumn!
        'emptyText' => 'No devices found',
        'tableOptions' => ['class' => 'table table-hover'],
        //'showFooter' => true, // required to move the filter row to below the table
        //'footerRowOptions' => ['class' => 'd-none'], // hides the footer row
        //'filterPosition' => \yii\grid\GridView::FILTER_POS_FOOTER,
        'layout' => "{items}\n{summary}\n{pager}",
    ]); ?>