Is it just me or does Nikkaf's Fatigue Resistance doesnt work as intended?

A bit of context on this: I got a nice ring with the curse of Energy Drain on my new playthrough and equiped it right away because i remembered it as one of the best curses with the least drawbacks, the drawback being -25% Fatigue Resistance.

But due to the heavy nerf to Vigor that saw most of its effects being tied to Survival skills that curse hits way harder than i expected it to, giving a point of Fatigue with nearly every skill i used at -5% Fatigue resistance with my Cloak and baseline Vigor. Because i really liked the ring and the curse i got Make a Halt, wich added an extra +10% Fatigue Resistance and -0.01 Fatigue Change to Vigor, wich put me mostly back to where i was before i got the ring, at least as long as i had Vigor on, with a total 5% Fatigue Resistance.

That meant i couldnt really do dungeons without Vigor on, so when i got into Denbrie with the Nightmares debuff i decided to clear it with Nikkaf, wich gives you +50% Fatigue Resistance. The issue here is that despite having 45% resistance for the whole dungeon i still gained fatigue at the same apparent rate and reached weariness despite the whole dungeon taking less than 1000 turns. I dont know the math behind gaining fatigue , but it feels like i should have at least gained it at half the speed i did.