Third try, two different walkthroughs... no "Chest Quest" yet

[Princess Vera]

Aargh, I'm so frustrated. I have followed two different walkthroughs assiduously for three playthroughs (I just got what should be the final chest before the final boss, so I'm about to beat it on nightmare), and this achievement is STILL eluding me. Is there a secret chest somewhere? A chest that's easily overlooked? One that appears after I've gone through an area and need to return for it later? An item that counts as a chest even though it's not one? A bug I don't know about? No one else has complained... is it just me?

Edit: I did try the Neoseeker guide on the last two playthroughs. And I do wear the Moon Lens constantly, and I obsessively check the mini-map and go into every useless building. I have a complex. D:

[Koby]

I don't recall any secret chests that wouldn't show up with Moon Lens. Also the achievement popped for me fine, so I wouldn't think it's bugged.

[Barefoot]

only one i know that is over looked is when your are in Heimdallr Underground and of course the game makes you go in the Dark Dragon's Nest but before you proceed go back out and get that one chest that on left side of Dark Dragon's Nest around the backside maybe?

[Barefoot]

or better yet do you have the Magius Master Quartz that will answer that if you have it

[Princess Vera]

I suppose I'll have to play it... a fourth time... and double-triple-quadruple check each area with the walkthrough, or something. Ah, well. I was hoping it was an easy fix.

[OmegaV-Rex]

Use psnprofiles guide. I got all 3 platinum trophy using those guide