I have to choose non-variable attributes to be able to add a variable product to cart in POS.

[behzadbx]

When I create a product in Woocommerce I add some non-variable attributes to my products (like fabric, description, etc.). Now when I want to add a product to cart in POS, I have to select every non-variable attribute so that the Add to Cart button enables and I can add the product to the cart. Why would I have to choose a non-variable attribute in order to add the product to cart? It shouldn't show the non-variable attributes in the first place.
I've attached two pics showing the situation.
Doesn't enable Add to Cart button when non-variable attributes aren't selected
Enables Add to Cart button after non-variable attributes are selected