Obtaining 9 charcoal unlocks the Block of Coal recipe (as well as the Coal recipe, obtained from blocks of coal). Presumably, this should only happen when you obtain 9 coal.
MC-117471
Obtaining charcoal unlocks Block of Coal recipe
Resolved
Fixed
2
Confirmed
charcoal, coal, coal_block, recipe, recipe-book
Minecraft 1.12 Pre-Release 2
Minecraft 1.12 Pre-Release 3
Retrieved
This looks like a simple problem of the advacement for the recipe not specifing the data in the json file.