Brand carousel show only parents

Hi there,

I need to create a Brand Carousel to be shown in home page but i need to include only Parents brand, i tried to add the following key value:

only_parents="true"

But it doesn’t work, is there any way to achieve that?
Full shortcode i’m trying is the following:

[pwb-carousel items=”30″ items_to_show=”5″ items_to_scroll=”1″ image_size=”thumbnail” autoplay=”true” arrows=”false” hide_empty=”true” only_parents=”true”]

Thanks