Free Shipping on Specific Categories


I have set up a free shipping promo for specific categories. The promo is working properly except for when a customer adds products from a category eligible for free shipping and, products not eligible for free shipping. In that case, the customer always gets free shipping. My hope is that they would be charged shipping for the ineligible product only.

The only conditions I have are:

Order over 75

Customer is in the USA

Categories In: my list of categories

Can someone confirm if what I want to do is possible?