lowering resist doesn't work

I decided to test what would be better, +2 to skill stones or -75% cold resistance, for this I took The Pandemonius Lapis Amulet
And the amulet I created for +2 to skill stones.
In the build there is nothing on negative resistances, only damage samotrel and grenades. on my and the test was conducted on the bosses 4 act at my level 52 when the level of the location 45.
In the end, 10 attempts each, it turned out
503-1200-1734 +2 levels
508-1155-1620-75% resist.
from which I conclude that it is impossible to remove resistances.

Yup tested as well and the pandemonius don't work