Why does the size option bug persist in the Fashionopolism theme?

Hi Team,

We are experiencing a size option bug when using the swatches style in the Fashionopolism theme.

As the below screenshots shown:

No matter which size we choose, it stays at S on both the product and checkout pages!

Could anyone kindly advise what is the likely cause and how to fix it.

I really appreciate your help in advance!

Cheers!

Hello Dear,
Welcome to Shopify Community

Thank you for your Question, I can try to solve this if you give me your site URL And pass.