Force Core in slot 3-4 not

The Force Core in slot 3 and 4 can not work? Correction

Im sure we need EP3 files for that function.

Correct me if im wrong but I think this is the case.

Force cores work in the 3rd slot, I know that for a fact. I don't know about the 4th slot, though. Most likely it does work, but it has a very low chance of succeeding.

FC is worked with 3rd slot, not sure 'bout 4th one cuz I tested with 3 slot item (2 slot then add one slot by Slot Extender).

I will describe the understanding.
Bringing the item or item 3 slot with 4 slot to upgrade with Force Core will not be able to piece the item to the npc to upgrade item can not be put in the box to Force Core upgrade now.
Here correction work?.
Or can be made to work? Item 3slot and item 4 slot to upgrade to Force Core

lol
FC work for all ur slot
but anyitem have max option for itseft . when u creat 3 slot opted item like a max option. so when u got 4 slot opted ur item like not change and u see it not work
but in real it work correctly