If you shiftclick an item from a furnace/any other storage system into your inventory and it is the same as the on you have in your offhands (you shiftclick steak into your inventory when you have steak in your offhand) it doesn't stack.
MC-84345
Shift clicking items into offhand doesnt work like it should.
Resolved
Duplicate
1
I've encountered this too.
Here's how to reproduce: Put one torch in off-hand. Go to crafting table, and prepare to craft torches. Shift-click them.
I expected this would stack with the torch in off-hand. (This does happen when I craft torches without a crafting table). Instead, it creates a new stack.
Does not duplicate MC-84224! That one is about using shift-right click to place a block on a usable block, not about shift-left clicking to move a whole stack.