Hmm, I have completely altered the whole Character/Inventory screen and moved/replaced/resized every slot, it still works fine. Did you change the hierarchy of the slots or have some stuff overlaying them? I just had my items “consumed” when they were parented incorrectly, or the slot background was removed/hidden (as it’s used to detect the mouse clicks)
On my own I managed to disconnect every instance of the item struct by adding a new variable to it. After working all day on it it’s a true horror as I either loose all days work or have to reconnect everything which would take several hours as well and I still wouldn’t be sure if I catched all :-/ I guess this is some of the many struct bugs with UE4.7 which hopefully gets fixed in 4.8…