Unable to unlock all ghost weapons after 100% main island

[Fluxy~]

as the title says, I have beaten the game and all the side quests but I was never prompted to learn the last ghost weapon(black powder bomb). I have verified game files but it did not work. Does anyone know how to fix this?

[5ean5ean]

This may seem like a dumb question but have you spent any points on it?

[Fluxy~]

I do have 7 points to spend, however I am unable to spend the point on black powder bomb which is the last ghost weapon I am missing as it is greyed out.

[Mu'Ammar of Carthus]

Same thing happened to this dude.
So definetly a bug.
https://steamcommunity.com/app/2215430/discussions/0/4330852522336909183/#c4330852522336920244

[Fluxy~]

i don't think it's the same as I did not get the chance to unlock the ghost weapon