So just today I was updating my MCreator version being very happy that the Metadata bug was fixed, so my duplicator mod worked better. But, I ran into another problem. I tried to test how it worked in the test environment. I was glad to see that my item duplicator had worked, until I tried to pick up the duplicated item after I took out the non-duplicated item. It just... disappeared. I tried this multiple times but it happened over and over again. I'm really sorry if this is my coding error, but I don't think it is. I also tried replicating the mod with the same code, and that didn't work either.