4.16 Slate Canvas .Position Bug ?

Why is the position of the widget about the center of the screen, although it should be on the lower right corner ?

               SNew(SCanvas)
				+ SCanvas::Slot()
				.Size(FVector2D(128.0f, 128.0f))
				.Position(FVector2D(1176.0f, 664.0f))
				[
					SNew(STextBlock)
					.TextStyle(&TestGlobalStyle->TestFloatingPointsStyle)
					.Text(FText::FromString("+777"))
				]

My screen resolution is 1176x664, so UIScaling shouldn’t be the problem.

If i increase the X-Axis of the .Position every tick, it pretends to be a value further than my X-Resolution although it hasn’t reached the end of the screen.