Frenzy Barb Set Bonus Bugged (Horde of the Ninety Savages)

The 4 piece set bonus does not work properly. It is supposed to give 6% damage reduction per frenzy stack and double the duration of frenzy.

The damage reduction component is not affected by the increased duration and therefore will drop halfway through frenzy.

I cannot confirm whether this is the case with PC as well.