It means you already got that treasure. I'm guessing what happened to you is the same thing that happened to me - got stuck at 11/12 chests. It turns out that some of the chests that are guarded by packs of enemies disappear while there is an active main story quest - for me, more treasure chests (and the enemies guarding them) appeared after finishing the main story quest as much as possible.
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Thank you very much for the effort it will serve me a lot as a guide.
Thank you so much too, Captain!
the 3rd chest in my location is disappear, there no platform to go up or the hook mechanich.
is it just me or a bug?
It means you already got that treasure. I'm guessing what happened to you is the same thing that happened to me - got stuck at 11/12 chests. It turns out that some of the chests that are guarded by packs of enemies disappear while there is an active main story quest - for me, more treasure chests (and the enemies guarding them) appeared after finishing the main story quest as much as possible.