I can confirm that this constantly works when using recipes where you "click and hold for more" and hold shift whilst moving your mouse on and off of the recipe you have the ingredients for. Along with less often for recipes that you don't have to "click and hold for more".
Steps to replicate with "click and hold for more" recipes: 1. Get a stack of wood planks in your inventory (any kind of planks) 2. Find a recipe that requires either plank types and asks you to "click and hold for more". 3. Whilst holding down click on the recipe, hold shift for multiple item crafting. 4. Quickly move your mouse on and off of the version of the recipe that you have the planks for. 5. Watch as it repeatedly gives you more planks.
Steps to replicate with normal recipes: 1. Get the items you need for a single item to be crafted (I initially tested with 5 diamonds for a diamond helmet) 2. Repeatedly click on the recipe and onto another recipe. 3. Watch as the item duplicates rapidly
As an additional /recipe give usernamehere minecraft:book results in commands.recipe.unknownrecipe and i can confirm that in 17w13b the book.json file is missing from /minecraft/assets/recipes/
I can confirm that this constantly works when using recipes where you "click and hold for more" and hold shift whilst moving your mouse on and off of the recipe you have the ingredients for. Along with less often for recipes that you don't have to "click and hold for more".
Steps to replicate with "click and hold for more" recipes:
1. Get a stack of wood planks in your inventory (any kind of planks)
2. Find a recipe that requires either plank types and asks you to "click and hold for more".
3. Whilst holding down click on the recipe, hold shift for multiple item crafting.
4. Quickly move your mouse on and off of the version of the recipe that you have the planks for.
5. Watch as it repeatedly gives you more planks.
Steps to replicate with normal recipes:
1. Get the items you need for a single item to be crafted (I initially tested with 5 diamonds for a diamond helmet)
2. Repeatedly click on the recipe and onto another recipe.
3. Watch as the item duplicates rapidly