Product filter shows out of stock items

Dear,

Using the sidebar containing the filter items such as the size of clothing items, we are able to filter out products and their variations.

We did however notice that if we filter on the size (for example “size:M”), that it shows the products with this variation available. This makes sense!

The problem is the following: we filter on size “M”, and it shows all the items with that variation existing. It does however not take into consideration the variations that are out of stock.

This is weird since users would filter on their size -> click on the product -> find that their size is not existing since it is out of stock.

How could we resolve this?

Thank you very much in advance for your time and support!

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