I had unplugged it to plug my power meter into it. In doing so, and from further testing, I have determined that if the drive is plugged in on boot, it grabs the 15W PD profile. If plugged in while running, it only grabs 7.5W. The PD firmware does not seem to handle hot-plug at 15W.
On boot:
on hotplug (showing zero draw because the drive powered down due to power constraints):
