There's an event set up to make an enemy with an entity ID of 1410150 not respawn on death, and an enemy with that ID doesn't exist in map data (very unusual). This titanite demon has an ID of 1310150, which both disobeys the map ID schema (m14_1 is izalith) and is never referenced in map events.

I want to believe that was an easier way to get it to keep respawning when they decided it should, rather than removing the code once it had been put in