No, I Didn’t die during the boss fight. i was able to get the cerberus cube in the 190 dungeon but the cube for fire lord didn’t drop. it died before the opening in its chamber. and yes i walked and tried to stick on the wall and i didn’t get anything. this happened in 130 dungeon also 1 time turns out the cube has fallen through the glass floor. but this time i walked on the glass floor in the fire lord chamber even though its a bit far from where it died. Am i the only one experiencing this?
anyway i hope they fix the cubes from falling through the glass flooring as well as some mob drops that falls through it in some areas.