It was hidden in plain sight( but not so much obvious as you had to read the cards), but I believe that the two missing chest can only be obtained solo. Yes, you read that right solo'd. How did I come up with such a crazy theory? Simple your VoG grimorie cards, there you find that someone had discovered the VoG and attempted to do it alone. He succeds up until the templar. I believe if you can solo beginning to after templar you will get the two missing chest. It is very far fetched I know. But this is the only theory not tested that correlates with the back story of VoG. Not doing the theory as I am only interested in the story of destiny.