Is Kylo Ren mastery bugged?

[Thoughtkriminal]

The mastery stat on Kylo Ren states that it increases his defense penetration. However, when looking at his stats the defense penetration value is zero. Further his resistance penetration is increased to a value 2x his mastery. Considering that all of his abilities do physical damage, resistance penetration is totally worthless. Is this a bug, or am I missing something?

[EA_Gunner]

Check this report.

[Thoughtkriminal]

Thanks for the response I will just add that it would be nice if the stat didn't always show zero to eliminate the confusion.