how do i prevent lighting from destroying items

I have boss mobs that drop very important items, and the best method of killing them is with modded swords. These swords spawn lightning whenever they hit an entity. However, when you use those swords to kill the boss, I'm assuming the lightning destroys the item, because in testing, the items don’t spawn after the boss's death. Either the lightning is destroying the item, or something with the sword being modded is preventing the items from dropping. Any help is appreciated.

note that the bosses are also immune to lighting