Wholesale fixed discount on variations

Hello! ??

I’m trying to set discounts for wholesale in a way that the variations of a product in the cart receive discount as if it were a product.

For example, I have “X” product that has the variations “a”, “b” and “c”. I want the discount N for be applied each item for those who buy more than 15 items of X (for example, if the customer buys 5 of each variation of X, the total 15, the discount should be applied).

I’m trying to create this discount using lists and rules to make the discount work in the plugin, but I’m not able to save the fixed amount to be discounted ?? After I save the field appears blank and when I test the product discount does not applies.

I noticed that the plugin also adds “Quantity Based Pricing” tab for the product. It has some way that I can use “interval rules” to be calculated in cart considering the parent product instead of variations?

Thank you very much!
I hope you can understand what I’m trying to do >///<