Put the summary of the bug you're having here
when a furnace is full it deletes the coal/charcoal you try to place in the furnace. just like the inventory thing.
What I expected to happen was...:
i expected my item to go to my main inventory. from my hand inventory,
and what happened is that my inventory was full,

What actually happened was...:
and it ended up deleting my item, i tested it multiple times. it kept doing it.
so if you have a full inventory it wont move your items. it deletes them.

Steps to Reproduce:
1. have a full inventory
2. try to move item with SHIFT to a full inventory
3. then it will delete your item you tried to move, NOTE this is all on HardCore Mode