Completed grasp of avarice solo without dying and when I went to collect the chest the game crashed then when I got back on it had me checkpointed at the second to last encounter as if I hadn't passed it and none of the triumphs or gear appeared in my inventory.
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Unfortunately the run will need to be done again and Bungie won't push the missing loot to your inventory. On a side note, looking at the PGCR for the run - it has a recorded death so the triumph wasn't going to unlock had you not crashed.