Exclude category products from the free shipping threshold

Hi,

I want to set free shipping for orders over a value of 500, but products from a specific category should not count towards that 500 total. I tried setting this up in your demo with shipping zones and classes, but it didn’t work as expected. Instead of showing a shipping cost when conditions aren’t met, the option disappears entirely—either it’s free shipping or not available at all.

Is there a way to achieve this setup in PRO? Thanks for your help!