From what I've been experiencing, you don't need to complete each game to find ghosts. If you find one, they'll accumulate in your count. I seem to be capped at 45 and I should be at 50 now.

Edit: I should be at 52 or 53 by now and I'm only at 46. I only got my one extra ghost count by finishing the game.

Edit 2: I just got the 50 achievement BUT the game isn't counting each ghost now. I found at LEAST 3-4 in my last round and I was given credit for only 1.

Are you sending your score? It seems to only count them if you send you score (even if you've already sent it 10 times).

I never had to for the first 45 ghosts. I just solely had to find them; didn't matter if I finished the game or not. Once I reached that number, approximately, it didn't matter how many ghosts I saw, the number just would not change. I tried an experiment to see what would happen if I finished each game and no matter how many ghosts I found while playing, I was only getting my count raised by 1 each time. I can certainly tell you that I found more than just a single ghost in the some of the last 5 games lol!

can you possibly shed any light on this, please?

I am having this problem too. It would count all of my ghosts whether I sent score or not. Today it is only giving me credit one per each game. (I too have hit the 50 mark and am working at 100 now).

[edit] Now seems to be working OK. Odd.

I am also having this problem. I send the score, I'm not at 10 scores sent yet either, and when it's a game where I know I saw 3 or 4, even at least two, I get only one added to the score on the achievements page when I check and refresh it. I'm wondering if there's just a delay in the count? I hope this is resolved, it didn't seem to happen to me before...

Edit: It only happens sometimes now. Right after I posted this it started counting... Weird...

I went to go test it out but could not find it on the games page. I know I stopped at 150/250 BC of still having small issues, but cannot confirm about now since I don't see a link anywhere :)

it was at the time, but I do recall near the end again when I'd see several ghosts and was not getting credit for all of them. This was a few days after my initial post/edit. When it comes back up I will definitely give it a poke again and let you know :)