I don't know if its the same for others, but it seem like its the "dumb enemies" feature that causes some fights to not work (more specifically almost everything in the challenge section). I think the problem is that the game automatically fail you if you don't receive a certain amount of damages, because I if turn on "damages multiplyer" and turn off "dumb enemies", the battles suddenly works. I think a fix for it would be to somehow be able to put neg status effects on ourselves that drain at our health? Though I don't know if that even possible to do.