Was playing this stage with Paganini + Pdxdash, and about 17minutes into the stage we realized we were getting no EXP from the enemies. (The purple text appears but the characters didn't gain any). We tried this with different hosts and remade to test the game was not bugged alone. Tried other...
In area 22, right at the end is a set of boxes.
(You are required to ignore warp to area 23 but press a switch next to it, smash a wall down and take the warp there to these boxes).
Every single time I have hosted the game on my HC account the 'scape box' is an empty box.