ContentView.swift

//
//  ContentView.swift
//  Shared
//
//  Created by Mohammad Azam on 6/27/20.
//

import SwiftUI

struct ContentView: View {
    
    var columns: [GridItem] = [
      
        GridItem(.flexible()),
        GridItem(.flexible()),
        GridItem(.flexible())

    ]
    
    func headerView(_ index: Int) -> some View {
        Section {
            Text("Section \(index)")
                .padding()
                .foregroundColor(Color.white)
                .font(.title)
                .frame(maxWidth: .infinity)
                .background(Color.blue)
        }
    }
        
    var body: some View {
        
        NavigationView {
            ScrollView {
                
                LazyVGrid(columns: columns, spacing: 10, pinnedViews: [.sectionHeaders]) {
                    ForEach(1..<11) { index in
                        
                        Section(header: headerView(index)) {
                            
                            ForEach(0..<20) { _ in
                                Rectangle()
                                    .fill(Color.red)
                                    .aspectRatio(contentMode: .fit)
                            }
                        }
                        
                    }
                }.padding()
            }
            
            .navigationTitle("LazyVGrid")
        }
      
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

There's a new behavior where SwiftUI compares the UUID's for each item, which apparently creates a problem in the nested ForEach loops. See post.

I was able to solve in your sample using the same technique.