SwiftUI - Why doesn't my .alert window change my state variable? - swiftui

Question

The incomprehensible thing is that if I set breakpoints when debugging, I get my desired result. But now to the problem:
I have a view, which on appearance should check if errors have appeared in previous calculations. If so, then the SelectionView() should be called when the error is confirmed. However, this does not happen. The alert window remains rigid, and you cannot continue using the app.
The function ErrorCheck() returns whether there is no error: 0 ; a warning: 1 ; or an error where you should jump back to the menu: 2.
So if there should be an error, then after confirming the Alert window, the window should close itself and you should be sent to the SelectionView.
If I set a breakpoint at the line where the state variable should be changed, then the alert window closes, and you are sent to the SelectionView.
import SwiftUI
struct NearfieldCalibrationView: View {
#StateObject var ErrorviewModel = ErrorViewModel()
var Speech = SpeechModel()
#State var showAlert = false
#State private var Menu: Int? = 0
#State var isActive = false
#ViewBuilder func getView() -> some View {
switch Menu {
case 1:
SelectionView().navigationBarTitle("").navigationBarHidden(true)
case 2:
WMLoadingMeasurementView(Flag: 5)
case 3:
WMLoadingMeasurementView(Flag: 7)
default:
Text("")
}
}
var body: some View {
ZStack {
BackgroundView()
ZStack(alignment: Alignment(horizontal: .center, vertical: .top)) {
VStack {
Spacer().frame(height: 20)
Text("Hello-StackOverFlow").font(Font.custom("Baro Plain", size: 20)).foregroundColor(.white)
Spacer().frame(height: 20)
Group {
NavigationLink(isActive: $isActive, destination: getView) {
Button(action: {
if SpeakerSetup.count != 2 {
self.Menu = 2
self.isActive = true
} else {
self.Menu = 3
self.isActive = true
}
}) {
Text("Start")
}.buttonStyle(OutlineButton())
.simultaneousGesture(TapGesture().onEnded { Speech.Speech(text: "", StopSpeak: true) })
}
Spacer().frame(height: 20)
}
}
}
.onAppear(perform: {
if ErrorviewModel.ErrorCheck() > 0 { showAlert = true }
else {
Speech.Speech(text:"Hello-StackOverflow",StopSpeak: false)
}
})
.navigationBarBackButtonHidden(true)
.navigationBarHidden(true)
.alert(isPresented: $showAlert) { () -> Alert in
var button: Alert.Button
if ErrorviewModel.ErrorCheck() == 2 { button = Alert.Button.default(Text("zurück zum Menü")) {
self.Menu = 1; self.isActive = true }}
else { button = Alert.Button.default(Text("Ok")) {}}
return Alert(title: Text("Error"), message: Text(ErrorviewModel.ErrorList()), dismissButton: button)
}
}
}
}