Recently, I’ve found a strange behaviour on one WordPress/WooCommerce project: after adding Product Gallery Images and save, the images are not being saved.
If have such issue, here is a quick fix:
1. Login to your Admin Panel
2. Navigate to Left Menu -> Appearance -> Theme Editor
3. Open functions.php for edit
4. Insert the following code at the end of the file, above last occurrence of ‘?>’:
update_post_meta($post->ID, '_thumbnail_id', filter_input(INPUT_POST, '_thumbnail_id') );
5. Save changes