I had 10 Memory Vestige: Light items in my inventory and 10 in my postmaster. It won't convert to the legendary item needed to find my last prismatic chest. I tried deleting some and reacquiring them from the postmaster but still won't convert. I've now deleted and reacquired down to 5. Still nothing. Also stuck at 16 motes of light even after defeating the meatball 4 times. All triumphs for overthrow bosses, chests and visions of the traveller done. What's with this bugginess!?!!