Conditional logic not working anymore

Hello, I have dozens of product pages that uses your premium plugin. Since yesterday, the conditional logic stopped working: by clicking on PELLE -> CLASSICA / CAMOSCIO / PITONATO / BRILLANTINATO / ANIMALIER before it used to open another radio button menu. Now nothing happens and the console show the following errors. Do you know how can I fix it? Since this morning my customer are unable to place orders!

Thank you so much!

Uncaught SyntaxError: JSON.parse: unexpected character at line 1 column 1 of the JSON data
    parseJSON jQuery
    <anonymous> https://www.sandalisiniscalchi.it/wp-content/plugins/nm-woocommerce-personalized-product/js/nm-conditional.js:29
    jQuery 2
    <anonymous> https://www.sandalisiniscalchi.it/wp-content/plugins/nm-woocommerce-personalized-product/js/nm-conditional.js:27
    jQuery 8
    <anonymous> https://www.sandalisiniscalchi.it/wp-content/plugins/nm-woocommerce-personalized-product/js/nm-conditional.js:7
    jQuery 8
jquery.js:4:16510
Uncaught SyntaxError: JSON.parse: unexpected character at line 1 column 1 of the JSON data
    parseJSON jQuery
    <anonymous> https://www.sandalisiniscalchi.it/wp-content/plugins/nm-woocommerce-personalized-product/js/nm-conditional.js:29
    jQuery 2
    <anonymous> https://www.sandalisiniscalchi.it/wp-content/plugins/nm-woocommerce-personalized-product/js/nm-conditional.js:27
    jQuery 8
    <anonymous> https://www.sandalisiniscalchi.it/wp-content/plugins/nm-woocommerce-personalized-product/js/nm-conditional.js:7
    jQuery 8

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