Doryani's Prototype not working on some Ultimatum monsters

These rare monsters aren't affected by the "Nearby Enemies have Lightning Resistance equal to yours" mod of Doryani's Prototype.
The mods showm in the upper screen are of one such monster.



In the image I was wearing one with -87% lightning resistance (plus 12 from endurance charges, for a total of -75%) and it was working properly on other nearby enemies since they were "vulnerable to Lightning".
This should happen in every ultimatum in which they appear.