I thought yours was vegetable tanned bdude hence the color mottling.
I'm surprised that black dye doesn't take well to white tanned leather.
My understanding, and just reiterated in the SZ CCP thread, is that white tanned refers to leather that has been tanned white so that it can be dyed any color, evenly. I don't see why black would be an exception to this.
Also, it sounds like some of the latest batch from PNP were white tanned hence the jet black even black...