I use your Variation add-ons, and I don't know how to add different featured images for each variation like we can do manually in the admin.
I try this:
SKU - post_status - product_type - post_parent - (...) - featured_image
var1 - publish - variation_master - - (...) - image1.jpg
var2 - publish - variation_master - var1 - (...) - image1.jpg
var3 - publish - variation_master - var1 - (...) - image1.jpg
But I only have image1.jpg which appears so the featured image does not change according to the variable product.