Products are not excluded from other shipping methods calculations

Hi, first of all thanks for the plugin!

Free Shipping works fine, using the free-shipping class as it has to, so its the “hide other methods” option, but the “Exclude Free Shipping products from other shipping methods” I’m not sure if it’s not working or if I’m not understanding its purpose.

If I add any number of free shipping products to the cart it stays free shipping, but if I add a single product without free shipping to the cart then all free shipping products add to the calculation. I charge by piece, the shipping cost for 1 piece is 3 dlls, for 2-4 is 6 dlls and for 5 pieces is 9 dlls. If I add 4 free shipping pieces and a single no-free shipping piece the total is 9 dlls when I expected to be 3 dlls (4 pieces exclude free…).

So, is there something wrong or I missunderstood? in which case, what does that option realy do?

Thank you!