Hi,
If the images are not in the variants in the backend, then it's not an import issue.
Normally, there is a mechanism on the product details page to check if the variants have different images and if they do, the images column is displayed on the variants listing, and for variants without images, the system uses the images of the main product on the fly.
So what that means is that you must have at least one variant with an image, or that there is a problem in the view displaying the variants listing. It might come from an old view override.
So we'll need a backend access to check the variants and a link to a product page with the issue to check the situation.
You can provide that in private along with a link to this thread via our contact form:
www.hikashop.com/support/contact-us.html