Our Community Managers have checked inside both of your game accounts & this is the reply that they provided to us:
"I have checked both of the players and they have already finished the Ghost Hunting quest and have caught all 12 ghosts"
I assume you checked with this maps
Unfortunately usually there is no other way than to check them one by one
If all else fails, you could contact pixel support.
But in most cases you just have to check again, maybe with fresh eyes after a break.
MadameCurie I have exactly the same issue, only 11 of 12 ghosts found, and I have been through the map showing where all the ghosts should be and I have done everything, seems like there is an issue with the game.
If you have double checked every single one, then please contact support as I described above. Only they have access to your game. I‘m a player like you 😉.
Please be aware that support is on a short vacation. You can send a ticket and they will deal with it when they return.