Can't purchase Phasewalker skin because I already own a core item

Hello. I wanted to purchase the Phasewalker skin for Wraith. However, I'm unable to do so. I get the "you already own a core item" message. I only own the Voidwalker skin, including the animation, so I suppose that's the reason why I get this error. It's a tad bit unreasonable, do I really need to open god knows how many packs in hopes of getting the skin I want? Or is it a bug that could be resovled?