When shift clicking a split stack of items into an inventory of a block (furnace, chest, crafting table) it takes the whole stack of the same item in multiple item slots

For instance, when shift-clicking raw ore into a furnace in split stacks for even smelting, all of the split stack goes into the furnace.
It can be seen in the attached video. I only shift-clicked once on one split stack in the 16 copper, and all 64 went in, even though they are in different item slots. This happened again when placing the remaining 32 into the furnace afterwards.