I think Leap Motion would interferes the tracker. I didn't try this with leapmotion but I have the same experience with Kinect. When I turn on Kinect and Vive at the same time, the tracking of Vive helmet will frequently lose tracking, showing as gray flash in the view, and if I turn off the Kinect, the phenomenon disappears. Since leapmotion uses infrared light emitter which is same with Kinect, the interfere will also occur in tracker tracking.