no categories dropdown on lateral bar

When viewing a list of products, in the side bar, the categories and their products are listed: there is no dropdown.

If I click on the Filter (Filtre in French) button, in the off canvas side bar, the categories are listed with dropdwon.

I use the same widget, in both side bar, I don’t get the same result.

Is there a way to get drop down in the “standard” side bar ?

The page I need help with: [log in to see the link]