help with collectibles?

#1Id_Bang_Miss_KPosted 6/24/2013 8:50:49 PM
So I got all of the GPS caches, documents, and relics, but no achievement. I looked in the document screen and I apparently missed "Unknown: Mission Failed" but isn't that one you're supposed to get once you collect the very last collectible?

Is there anyway to fix this or do I seriously have to restart the whole game? Which I have since finished...
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