Can't find option when paste tray sim MCCC

So i was trying to past a child sim that i create on my main household child, i save the child i want on my gallery and load back to the game, but when i click on the child > MCCC > MC Cas > copy/paste > paste tray sim, the popup menu is completely blank, i make sure both of the sim is child and same gender

i thought child sim or younger is not available to paste using mccc but i do found some post saying it can. so i test it with adult sim but the thing is only the household i save from age ago appear, not the new one i save and i'm not sure how the system work