NavigationView back button not showing - swiftui

Question

Have a simple NavigationView with fixed content on both sides. The left pane just shows a couple of buttons and the right pane shows a graph using an NSView wrapped in an NSViewRepresentable. When viewing on iPad in portrait mode, the left pane disappears as expected but the 'back' button does not show. Can click in the area where the 'back' button was expected and the left pane shows up. There just isn't anything visible there.
What am I doing wrong?
var body: some View {
NavigationView {
VStack(alignment: .center) {
Text("This is the left side")
Button {
...
} label: {
Text("Create Estimate")
}.foregroundColor(Color.black)
Button {
...
} label: {
Text("Reset Results")
}.foregroundColor(Color.black)
Text("This is the end of the left side")
}
VStack {
Text("This is the right side")
AreaChartView(redrawCount: redrawCounter, scenario: activeScenario)
}
}
}
}
Update: This happens even when I comment out everything in the NavigationView above and replace with:
NavigationView {
Text("This is the left side")
Text("This is the right side")
}
Note that I created a new iOS project with nothing but this super-simple NavigationView and it shows the Back button just as expected. Since literally everything in my app's view except the NavigationView above is commented out, I'm wondering what else may be wrong in the environment. Note that my app is a multi-platform app rather than just iOS, though I don't know why that would matter.

Answer 1

OK - for any other poor soul who may encounter this...
When I found that even a trivial NavigationView had no 'Back' button (see question), it became clear that the trouble was not in the view code at all. Took some searching but discovered that somehow the default accent colors in the Assets file had been changed to white. This meant that the 'Back' button was white against a white background and was thus invisible.
Deleting these white accent colors causes SwiftUI to use defaults. Now the 'Back' button shows in blue as expected.