Question Screen goes black, just UI is being displayed as soon as I drag on Android, but works fine in Editor

I created an UIElement which can be dragged and works perfectly fine in Editor.
However, on my Android device when I launch it looks OK until I touch on the screen. As soon as I touch and try to drag it, screen goes black.

Is that a known issue or I am missing out on something?

_controlKnob is the element which gets dragged based on "event.position"

void Start()
{
_rootElement = _document.rootVisualElement;
_controlPad = _rootElement.Q<VisualElement>("ControlPad");
_controlKnob = _controlPad.Q<VisualElement>("ControlKnob");
_controlPad.RegisterCallback<PointerDownEvent>(OnPointerDown);
_rootElement.RegisterCallback<PointerMoveEvent>(OnPointerMove);
_rootElement.RegisterCallback<PointerUpEvent>(OnPointerUp);
_rootElement.RegisterCallback<PointerEnterEvent>(OnPointerEnter);
_rootElement.RegisterCallback<PointerLeaveEvent>(OnPointerLeave);
}