Make sure you have installed and Activated the “Vision core” plugin. Without Vision Core plugin you cannot register your product.
Also without the registration, the update feature won’t work.
Also, check the version of the vision-core plugin. It must be in version 1.1.9. in order to be able to update the theme.
If it’s not, please install it by following the instructions in this post:
After you have installed the vision-core v 1.1.9, the update should work.
Please let me know If after trying these solutions you still have no success.