Tenacity Up + Tenacity Down... how does this mechanic work?

"Huatimus;c-1312351" wrote:
Both give a bonus/penalty of the same amount so they effectively cancel each other out when they're both on the character. I.e. If you had 35% Tenacity before, you'll still have 35% Tenacity after and be subject to the usual Tenacity-Potency check.

I still don't think T-UP is working as intended. It has and still behaves like pure debuff immunity in all areas of game. I've never put a debuff through T-UP even with 90% potency and potency up abilities like on Jyn, TFP with EP lead...