Flask suffixes "reduced effect of Chill/Shock" not working correctly

I have 2 utility flasks on my character, one rolled with "of the Fox" and one rolled with "of the Sable" which give:
48% reduced effect of Chill on you during flask effect (of the Fox)
58% reduced effect of Chill on you during flask effect (of the Sable)

Which presumably should give me immunity to Chill while they're up, yet during mapping I still get Chilled often with active flasks. The Chill I receive is still significantly reduced, but it's not making me immune. If I had to guess they're acting as if they are multiplicative with each other rather than additive, or maybe only one is being applied at a time.

There were no "increased effect of Chill on you" mods on the map or anywhere else on my character that could mess with the math as far as I can tell.

I also have another pair of flasks which reduce the effect of Shock, but the same thing happens where I still get shocked.

not a bug, flask mods do not stack with each other.