Composite product quantity issue

The issue is when compostise product have other product select with custom quantity. Front displays only plus and minus icons, but there is no number input and customer can not select custom quantity.

Front (F12 console) shows code:

<span class="wooco-qty-input">
<span class="wooco_component_product_qty_btn wooco_component_product_qty_minus wooco-minus">-</span>
<span class="wooco_component_product_qty_btn wooco_component_product_qty_plus wooco-plus">+</span>
</span>

Is that a plugin bug or fault in my wordpress page?

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