Show Filters button is not displayed when sideContent disappear (on small device)

Question

I am tying to set up elasticsearch and I saw on the park example that there is a "show filters" button when window size gets small.

But I can't find the related settings for it on my actual program, I can see on inspection that the button is there with display: none but I can't find the related settings to activate it.

Looks like that:

<Layout header={ <SearchBox debounceLength={0} />}
    sideContent={
        <div>
            ...
        </div>
    }
    bodyContent={
        <Results  
            // @ts-ignore 
            resultView={CustomResultView} 
            className={styles.resultDiv} 
            titleField='name' 
            urlField='nps_link'
            thumbnailField='image_url' 
            shouldTrackClickThrough 
        />
    }
    bodyHeader={
        <React.Fragment>
            { wasSearched && <PagingInfo /> }
            { wasSearched && <ResultsPerPage /> }
        </React.Fragment>
    }
    bodyFooter={ <Paging /> }
/>

It seem to be like the park example so I really don't know why the button won't show.