Hello,
Theme Version 3.0.2.1 is compatible with WC 3.0.5. So, you may update plugin and theme. After that check, if problem is solved. If not then go to Appearance > Themes > install and activate official WC theme Storefront. Check if your variations work fine with default WC theme. If problem still persists then contact WC support of WC support forum. If your issue appears only if our theme is activated then reply back to this topic.
Regards