Possible Picture Frame Bug

[Teppelin's King]

So I am not entirely sure if this is a bug, but as far as I know, my current knowledge of the game leads me to believe so. So throughout the game I was collecting the picture frames. By the time I finished the Bonus World level I had 245/250. I later found the other 5 that I missedd. When I received my 250th a steam window popped up and it said I had "250/373" (I believe that's what it said- it disappeared quick). Anyway, I know that the picture frames unlock concept art, and that there are only 250 concept art pictures available in the gallery. So now the problem is that I do not have the achievement for getting all the picture frames in the game because I apparently somehow missed over 100 of them. Is this some sort of bug? I honestly don't think I missed over 100 picture frames somehow... is there really more than 250 hidden picture frames? Not sure if this is an achievement bug or not. Just thought I would report it anyway just in case.

[Linds]

There are 373 picture frames in the game (there are 2 x bonus worlds, as well as all the onces in the invisicrates through the other levels). This is exactly like the Xbox version. There are only 250 Gallery images though :)

[Teppelin's King]

Ah thank you, I am silly and did not see the other portal. Thanks!