We are trying to set up a 3 for 2 on our store.
Basically, for every 3 qualifying products, give 100% off the cheapest item, if 6 items are in the basket, then give 100% off the cheapest 2 out of the 6.
It works perfectly as-is with 3 products, but for more, it just seems to pull a random product and discounts that!
Internally the matching products are ordered expensive to cheap, then every 3rd item will be discounted. Those will not neccesarily be the cheapest items, but the cheapest item in every selection of 3 products.