Achievements "Seeker"

I have finished the entire game and bonus, and played the HOS and got gold stars in the extras.
I have received all of the achievements accept the "Seeker". I only got 2 stars and 250 objects.
My question is, how do I get the 3rd star when I have done everything that needs to be done?
Anyone else have this issue?

I have this problem as well.

Same here. I played every HOP in the game and bonus chapter.
I didn't play the bubble shooter just in case they didn't count the objects you get when playing the bubble shooter.
So I think it's a glitch.
I actually counted the items in the HOP's after I got 200 objects.
I had 240 items when the game ended.
So in the bonus chapter I should have gotten the achievement by the first HOP I played.
So this kind of blows when you by a CE for the achievements.

I got the "Seeker" (250) achievement by not doing the alternative bubble pop, I think it was at Mountain Plateau in the bonus game, but I didn't get the bubble pop achievement. Seems you can't win...