Ultimatum bug or a feature?

So I have 170% fire res when I started Ultimatum. 1st option I picked was "Burning Turrets" why not? So few rooms later"-15% All Res" option showed up and I took it, after that upgraded it to "-30% All Res" and wanted to see how bad things got. To my surprise everything got lowered except Fire res.


Wooping 90% Fire res! So maybe Turret challenge gives you ability to reach max res cap to said element, but it doesn't say anywhere. was it like this from start or it's a bug?