Works as designed. A Yakima roof box wouldn't stay straight with wind. It looked like the mounting hooks wouldn't fit around the wide bars. It might be better to use their cross bars with their products. I exchanged it for a Thule, and it seems to mount better, and hasn't moved.
OEM part fits like you would expect. Look good on the car but makes more wind noise. I'll try to tweak it to if I can reduce some of the wind noise. The Yakama bike tray I mounted seems rattle a bit also. I'll reach out to Yakama about that.