Hi there,
I checked and it was actually a bug in Hikashop. To fix it, I replaced in the view form_options of filter the line:
<?php echo $this->product_informationType->display("data[filter][filter_data_cursor]", @$this->element->filter_data, $this->fields , 'onchange="setVisibleUnit(this.value);"', ''); ?>
with this one:
<?php echo $this->product_informationType->display("data[filter][filter_data_cursor]", @$this->element->filter_data, $this->fields , 'onchange="setVisibleUnit(this.value);"', 'datafilterfilter_data_cursor'); ?>