Steps to reproduce

1. Create a behavior pack with a recipes folder and put the example recipe below in a json file in the recipes folder.
2. Apply the pack to a world.
3. Load the world, and put a stack of iron bars in a furnace, along with a fuel item.

Expected result

You get 4 iron nuggets from each iron bar.

Observed result

If the furnace output is empty you get 4 iron nuggets from one iron bar, but if there are any iron nuggets in the output slot you get 1 iron nugget from an iron bar.

---

When using furnace recipes with outputs greater than one, only the first instance actually outputs the correct amount. Subsequent results only produce one additional item and ignore the output count as stated in the recipe. Using a hopper to keep the furnace output slot clear alleviates this bug.

Example of recipe being used:

{
"format_version": "1.12",
"minecraft:recipe_furnace": {
"description":

{ "identifier": "minecraft:furnace_iron_bars" }

,
"tags": [ "furnace", "blast_furnace" ],
"input":

{ "item": "minecraft:iron_bars", "data": 0, "count": 1 }

,
"output":

{ "item": "minecraft:iron_nugget", "data": 0, "count": 4 }

}
}