Penetrate VS unbending

Is it a bug that it doesnt cut through unbending?
Used cunning on a unbending flight, used to work but it didn't proc.

Penetrate stopped working on a lot of skills/talents. That must be another one

It stopped working on Invalidate and since Unbending has similar effects to that, I'm inclined to agree with Lord.Rex and say that it's not supposed to work on it.

It's confirmed that Penetrate shouldn't work on these talents so I don't find it very useful at the moment.