I was just browsing the first couple of pages here to see if this exploit was a thing and it seems not. But when you get a calling where you have to defend a given zone aka the progress bar, you can go to any chest and open it without looting it. Repeat this 5 times and you are done with that calling.

Edit:
It is onlt for callings, not the thread of fate quests.
So far for me it has worked on all the treasures I have found, but there might be some cases of it not working.