Attribute filter does not honour custom ordering

I have added a new product attribute my site which shows the size band they are in (e.g. 0-20cm, 21 – 40cm, etc.) and set this attribute to have custom ordering. However, when I put this attribute into the filter the custom ordering is not being honoured; instead it shows the attributes in alphabetical order. Is there a way to fix this?

Thanks.

https://wordpress.org/plugins/woocommerce-products-filter/