Shipping not working for variable products

Hi,

The plugin is working for giving the cost of shipping for variable products like for this one: https://artchoy.staging0709.win/buy-art/ciudades-invisibles/andria-la-ciudad-y-el-cielo-diptico/ . It has the size and weight and does not work. I tried if it works with a simple product and it did: https://artchoy.staging0709.win/buy-art/uncategorized/test/ . I would like to now if there is something i am missing to do or if it is a plugin error.

Best Regards,

Alejandro Jimenez

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