I fixed it for us, but it’s not something people will be able to use unless they have access to the engine source.
I modified this function:
bool FSceneView::ScreenToPixel(const FVector4& ScreenPoint,FVector2D& OutPixelLocation) const
the issue seems to be that the screentopixel is using the ViewRect, not the UnscaledViewRect. You can see later in the source that the DeprojectFVector2D uses the UnscaledViewRect over the ViewRect, so this looks like an oversight in updating all the code that uses ViewRect while adding the function:
void FSceneView::SetScaledViewRect(FIntRect InScaledViewRect)
Is this already fixed in 4.7? I don’t have access to the preview source.