Hello Arthur,
Sincere apologies for getting you a late response. Kindly note our plugin is not yet compatible with the “YITH Product Size Charts for WooCommerce Premium” plugin. We have listed our plugin’s compatibility on our product page.
Would you mind sharing your website URL to check the issue. If this is a quick fix, we are open to make this customization for you. Looking forward to hearing from you.
Best regards,
INTOLAP SUPPORT