Hello, Jungeun,
Thank you for reaching out to us with your query. We understand that you want to ensure that out-of-stock variants are not selectable on your WooCommerce product pages.
To proceed with the troubleshooting process, we kindly request that you deactivate the XStore theme and instead activate the default WooCommerce theme, Storefront, by navigating to Appearance > Themes within your dashboard. This will help us determine whether the issue persists irrespective of the theme in use.
Best Regards,
8Theme’s Team