Simulator and preview show two different behaviors using GeometryReader

The simulator is on the left and preview on the right. Not sure why the padding is completely removed.

Here's my code:

            GeometryReader { graph in
                VStack {
                    ZStack {
                        Color("Background")
                            .cornerRadius(23)
                            .shadow(color: Color("Shadow").opacity(0.3), radius: 4)
                        VStack {
                            Text("Program Completion")
                                .bold()
                            ProgressViewCircle(progress: $progressValue)
                                .frame(width: 150.0, height: 150.0)
                        }
                    }
                    .frame(width: graph.size.width - 30, height: graph.size.height / 3 )
                    .padding()
                }
            }