Is the Chest Count bugged?

[Adaaification]

Okay, i have the following problem. I did everything you can do. Im New Game Plus 2 at the moment and i was just now able to defeat the damn Dragon Boar. And i stay at 179 out of 180 chests. But according to the map i did everything. And for the record im playing on X Box. Here is a list of whats done:

Purvanna 19/19 (Completed: Booty Cave, Ruined Castle, Mowtallikas Concert, Polaris Ruins, Furrlon Cave, Golden Tower)
Straits Island 4/4 (Completed: Ice Pirat Hideout)
Lovepurr Island 4/4 (Completed: Squeaky Cave, Lovepurr Castle, Lovepurr Cave, Antares Ruins, Orion Ruins)
Twin Islands (Completed: Twin Castle)
Pawman Isles 2/2
Long Island 4/4
Catuga 3/3
Purricade Island 3/3
Code Island 1/1
Sandy Islands 2/2
Infinity Tower (Completed: Infinity Tower)
Twilight Isles 7/7 (Completed: Centauri Ruins, Heartpurreak Cave, Oinker Maze)
Sunset Islands 16/16 (Completed: Eight Bit Dungeon, Fire Pirat Hideout, Spicy Cave, Volcano Mountain)
Furrgy Island 7/7 (Completed: Pirat King Hideout, Doggy Jones)
Zero Dimension 3/3

All 12 Wanted Posters are complete and finished is the Macho Dog and the Dragon Boar (They arent part of the Wanted Posters but just to be careful here to include them). Plus the Gentlebros Secret Chest is found. The quest with the missing items (Vodoo Doll, Hammer, Milk) is also done. And so ist the mermaid questline. The blue stones are also done.

Equipment is complete, Head 26, Body 25, Melee 18, Ranged 10, and Trinket 25. Magic is 10, Ship is 17 and Quests are 52.

So what the heck im missing? Is there still something secret i dont know about? Or is it just a bug?