Is unity 5.5 holographic emulation conflict with the 3d UI？

Question

Before using holographic emulation，I can get the UI correctly： get correct UI

But after using holographic emulation, I can't get the UI correctly.

when I move the cursor to another position, the UI get??

I use this way to get UI:

            PointerEventData pData = new PointerEventData(EventSystem.current);

            pData.position = new Vector2(Screen.width * 0.5f, Screen.height * 0.5f);
            pData.delta = Vector2.zero;
            pData.scrollDelta = Vector2.zero;

            List<RaycastResult> canvasHits = new List<RaycastResult>();
            canvasRaycaster.Raycast(pData, canvasHits);

            if (canvasHits.Count > 0) //process

who can help me? I guess this is a unity bug.