move things around in your ships hold, they may be under something. Or you completed the quest and they did not come out of your quest menu. In this case you need to go back to the monger you took them to and dbl clk him again depending how many you had for him and you may need to go back to the monger who gave it to you and do the same thing. This is a known bug and we hope they fix it next publish. Do not cancle quest as this will hurt your standing with the mongers.