Swatches shows as image instead of Size

Hello i have a problem

i have different types of clothes. all have different colors except one. one is only available in black. and there the problem is. in this product, it does not take the size, it does take the image. but there is no switch for color, only for size. and so the size is not showing in Size, it is the product image and this confuse many of my clients and it increases the risk of wrong size ordered. how can i change? i send you two examples here:

the hoodie rope is the wrong one. it is only available in black. here you see the swatches is in images but for the size: https://justbe.kim/produkt/be-wild-hoodiekleid/

and here is an other example. here it is correct. you can choose between colors and the size swatches are correct: https://justbe.kim/produkt/be-wild-enganliegendes-oeko-shirt/