there is a bug with hoppers when you point them to go on top of the furnace to smelt iterm

Put the summary of the bug you're having here

What I expected to happen was...:
i expected the items to go into the furnace to start smelting

What actually happened was...:
hoppers that are pointed to the top of the furnace are not working properly, when you first put the material in, it will put in about 2 of whatever it was you put in the hopper than disappear out of the hopper and can not get back. then if you put anything in the hopper after than nothing will go in at all

Steps to Reproduce:
1. get a furnace and put a hopper on top of it pointing towards the furnace (there does not have to be any coal in the furnace)
2. put something in the hopper or in the chest (if you decide to put a chest, same thing happens either way) and about 2 items will go into the furnace. when it stops and you look back into the furnace, the items are gone
3. ...