SwiftUI Observable object doesn't update UI on first attempt - swiftui

Question

Issue
The #ObservableObject ViewModel only updates the UI after closing and re-opening the view. Once this update has happened, every subsequent change in the #Published var inside the #ObservableObject triggers an automatic update.
Context
I have a model called 'Stack' in my project.
struct Stack: Identifiable, Equatable {
var id = UUID()
var title: String
var isPinned = false
}
I have a view (NavigationMenuView) which presents all of the stacks in a scroll view
import SwiftUI
struct NavigationMenuView: View {
#ObservedObject var viewModel = NavigationMenuViewModel()
#EnvironmentObject var environmentObjects: EnvironmentObjects
var body: some View {
ZStack{
NavigationView {
VStack(alignment: .leading){
ScrollView {
ForEach(viewModel.stacks){ stack in
StackRow(
stack: stack,
lftButtonAction: {
self.viewModel.toggleIsPinned(for: stack)
},
rhtButtonAction: {
self.viewModel.deleteStack(stack: stack)
}
)
}
}
}
.navigationBarTitle(Text("Home"))
.navigationBarItems(trailing: addNewStackButton)
.background(Color(UIColor.systemGray6).edgesIgnoringSafeArea(.all))
}.zIndex(1)
if environmentObjects.newStackViewIsShown {
VStack{
Spacer()
NewStackView(viewModel: NewStackViewModel())
}
.onDisappear{
self.viewModel.fetchStacks()
}
.zIndex(2)
}
}
.onAppear{
self.viewModel.fetchStacks()
}
}
}
The view model for this view has a #Published var stacks = [Stack]() array which gets updates by fetchStacks().
The NavigationMenuView has a subview (NewStackView) which creates a new 'stack' (using the ViewModel) using this button:
Button(action: {
if !self.isAddButtonDisabled{
self.viewModel.addNewStack(title: self.title)
self.environmentObjects.newStackViewIsShown = false
}
}) {
Text("Add")
.padding(.vertical, 16.0)
.frame(minWidth: 0, maxWidth: .infinity)
.foregroundColor(Color(UIColor.systemBackground))
.background(
RoundedRectangle(cornerRadius: 10, style: .continuous)
.foregroundColor(addButtonColor)
)
}
.disabled(isAddButtonDisabled)
My own progress
I have found out that this only occurs when the NewStackView is presented as a subview of the NavigationMenuView. When presenting it as a modal view using .sheet() the NewStackView updates straight away.