When previewing a recipe (without the required materials) in a furnace while its being fed by a hopper, items will be fed into the furnace which overlaps with the recipe preview.

Expected behaviour:

It'd be expected that the recipe preview should disappear when the furnace is being fed items.

Actual behaviour:

The recipe preview remains under the items entering the furnace.

Steps to reproduce:

1. Place a furnace with a hopper feeding into it and fill the hopper with cobblestone.
2. Selecting a recipe in the recipe book (make sure you don't have the materials within the recipe)
3. Observe the furnace being filled up while the recipe preview remains.