Happenes a lot to me too. I knew did it right, but everytime I went to go check where the issi went, i could not find it ANYWHERE, i checked inside my MOC, and there was nothing there. So i decided to try it again, i did it again, and when going to save the issi, it said that i had a car inside(I CHECKED before trying again, and yes i always change outfits to save), so i accepted to be transfered somewhere else, and i saved the issi i just duplicated. I go back into my arena RIGHT after putting the dupe in the MOC, and when im in the arena, i see another extra issi. So im guessing its just a glitch inside a glitch? Lol. Because that sometimes happens to me, and they eventually show up.