Goods from the islands have different probabilities of being received. That is why your ship may not bring all of them. The higher the probability you'll receive particular goods, the better your chances are that you'll find them in the ship's hold.
The round indicator for the item and its color show the probability you'll receiving it: - If the indicator is fully green, you will receive the product. - If the indicator is light green or yellow, you will probably receive the product. - If the indicator is orange or red, you will probably not receive the product.
You can find more information on how to increase the probability of receiving rare items in the relevant article.