Flask Enchant "Used When Charges Reach Full" Not Working in Ultimatum Boss Encounter

I've been farming the Ultimatum boss for a while, with over 10 encounters, and four times I got randomly one-shot by the Trialmaster. Couldn't figure out why, but now I see that my 'Taste of Hate' isn't working (I use Mageblood, so this is the only flask I have with this enchant).

After entering the boss fight after round 10, even when I hit the flask and it fully recharges, the enchant still doesn't work.

Also, there's no Ultimatum mod messing with my flask I didn’t pick "Cannot Gain Flask Charges" and my flask still gains charge.

Edit: I've also tried it with the 'Reused at the end of this flask's effect' enchant, and this doesn't work either.

I am having the same problem, my flask was running when I entered the arena but it just didnt activate again even though I had the charges,

this has happened to me twice first time I thought I just didn't have my flask up due to it ending right as I hit the transition

since im running a wardloop build I immedietlly kill myself when my flask doesn't work, so rip getting the challenge I guess

As of the Necropolis league, this bug is still NOT fixed.
I hope GGG sees this and fixes it, just seems to be something that can be patched out easily...

Still this bug is in the game. Fix ya game GGG

GGG please fix this, such a stupid issue for such a long time.