Tenacity Bug?

I can actually vouch; this happened to me today as well while playing GW with my clones team. A random IGD inflicted defense down while my tenacity buff was still up from Rex. I didn't think to take a picture because I thought it might finally be working as intended; when a toon has Tenacity Down, they are still able to resist effects (I get that that might come from the inherent resist chance of each character), so I thought they might have finally changed the game to allow toons with Tenacity Up to have a debuff placed on them.