Simple issue here: The Night Lich (and possibly other bosses, haven't tested) will drop nothing if not killed directly by damage from a weapon. This means that, for example, Fire Aspect and Flame will result in the Lich dropping no items, as well as mods that add magic weapons (tested with the spells from Wizards RPG Series). Tested on version 1.7.4 due to being the only one compatible with 1.20.1 (playing the Prominence modpack). If intentional, a config setting would be helpful to allow for mod compatibility.