Problem about regular and sale prices

If I follow you correctly, you are referring to the price that appears under the product name, like this;

But with variable products, it appears like this;

No regular price and no strike-through. Unfortunately, that is a function of WooCommerce themes that Markup-by-Attribute does not have any control over. I think you’ll find that WooCommerce behaves this way with or without the plugin installed.

Please let me know if this is not what you are referring to.

That is exactly what i was asking. Thanks anyway.