The bug
Shift clicked items are not moved in other valid slots if the first slot the item would be valid for cannot take the item for example because it contains a different item, it contains already a full stack of the same item or the slot has special stacking restrictions.
Affected situations
Last updated for 19w34a
Blaze powder in brewing stand being a valid ingredient and fuelFixed in 19w34aLogs in furnace being valid item to smelt and fuel
How to reproduce
Place a brewing stand
Put a blaze powder item in your inventory
Open the brewing stand inventory and shift click the blaze powder
→ The blaze powder item moves into the ingredient slotPlace a different item in the ingredient slot
Shift click a blaze powder item
→ You will notice that it does not move despite it being a valid item for the fuel slot
Code analysis
Based on 1.11.2 decompiled using MCP 9.35 rc1
The methods overriding net.minecraft.inventory.Container.transferStackInSlot(EntityPlayer, int)
return an empty item stack if an item is valid for a slot but cannot be placed in it, for example because there is already an item in the slot. Instead it should try all other valid slots before returning an empty item stack.
also appears in 1.15.2 for the furnace