if i remember correctly, the images are not migrated automatically, you have to manually move them from old (/components/com_virtuemart/shop_image/) to new ( /images/stories/virtuemart/)directory before sync.
In virtuemart configuration (when executing sync) the images are then auto added to products.
Please check this link for more info: http://emanipur.org/blog/item/157-migrate-virtuemart-119-to-2xx-without-losing-any-data