Sheet freeze in SwiftUI when parent-View gets updated

Question

Using Swift5.3.2, iOS14.4.1, XCode12.4,

I am showing a modal sheet in SwiftUI.

Unfortunately, the sheet completely freezes whenever an underlying parent-View re-renders/updates.

I am absolutely clueless on how I can circumvent that issue. Any ideas ?

Here is the parent View:

import SwiftUI

struct ParentTrialView: View {
    
    @State var currentDate = Date()
    @State private var showingGrid = false
    let timer = Timer.publish(every: 10, on: .main, in: .common).autoconnect()
        
    var body: some View {
        
        NavigationView {
            Text("\(currentDate)")
                .onReceive(timer) { input in
                    currentDate = input
                }
                .toolbar {
                    ToolbarItem(placement: .navigationBarTrailing) {
                        Button(action: {
                            showingGrid.toggle()
                        }) {
                            Image(systemName: "square.grid.3x3")
                        }
                        .sheet(isPresented: $showingGrid) {                            
                            ChildTrialView(onDismiss: {
                                showingGrid = false
                            })
                        }
                    }
                }
        }
    }
}

And here is the child View:

import SwiftUI

struct ChildTrialView: View {
    
    var onDismiss: () -> ()
    
    var body: some View {
        
        NavigationView {
            Text("Trial")
                .onTapGesture {                    
                    onDismiss()
                }
                .toolbar {
                    ToolbarItem(placement: .navigationBarTrailing) {
                        Button(action: {
                            onDismiss()
                        }) {
                            Text("Cancel")
                        }
                    }
                }
        }
        
    }
}

If you, for example, set the timer to 20 seconds. Then you have 20 seconds where everything works on the child View (i.e. it's tap-Gesture works, and also its Cancel button to close the child-View works perfectly).

However, when the timer fires an update to the parent-View, then no action works on the child-View anymore !!

I am more than desperate with this SwiftUI problem.

Any solution on this ?