Never seen this happen to me before, and I apply minimum 15 debuffs every time I use my empire team, which is my main team and basiclly the only one that is arena viable that I have. I hate whenever I see tenacity up, because it brings my debuffs applied to 0, and have never seen any bug that has made it work otherwise. Of course, once I have my b2 geared up a bit more I will say bye bye to tenacity up (and taunt), but until then, dang you tenacity up, which I have never inflicted a debuffs through.