Hello,
We don’t give guaranty for full theme compatibility with all 3-rd party plugins and we did not test XStore with this plugin. Sometimes, not always, you need additionally customize the theme or plugin to make them work together. Unfortunately, it’s not possible for the author to make the theme compatible with all the existing plugins and additional customization is outside the scope of our support.
Our demo https://xstore.8theme.com/ uses Variation Swatches, please watch this video tutorial – https://youtu.be/LgzC4iK-j6A It this is what you are looking for, you can disable the plugin and enable our Variation Swatches.
Regards