The bug
When using a grindstone it always sets RepairCost:0 in the NBT of the item (except for books, see MC-148476), even though that is redundant because 0 is the default if no value is present.
Due to MC-129057, this prevents the recipe book from using such items (e.g. bow for dispenser recipe or fishing rod for carrot / fungus on a stick) because it does not ignore RepairCost:0 and therefore considers it custom NBT data, which should prevent using the item for recipes.
Reproduction steps
Put a bow in your mainhand and enchant it
/enchant @s minecraft:unbreakingPut the bow in a grindstone and remove its enchantments
Try using the bow as part of the dispenser recipe by clicking on it in the recipe book
❌ It refuses to use the bowInspect the NBT data of the bow by putting it in your mainhand and running
/data get entity @s SelectedItem❌ The NBT data of the bow contains
RepairCost:0
Linked issues
Comments
marcono1234
Yes of course, no problem!
pine1needle
The part about the recipe book not using items is MC-129057, but it is probably a bug that the grindstone leaves the "RepairCost: 0" NBT tag.
I have had this issue with crafting warped fungi on a stick in 20w17a; fishing rods that have been repaired using a grindstone cannot be used to craft one even if their durability is full.
pulpetti
In 1.16.1 and 20w29a.
Avoma
Can confirm in 20w46a.
ampolive
Can confirm in 1.17.1.
ampolive
Can confirm in 1.18 Pre-release 1.
gnembon
I have made some edits to your report, I hope this is alright for you.